docs(tutorial/index): improve accessibility

- Adds accessibility attributes to links and images.
- Adds a note on using NVM for node.

Author: Sharondio

docs/content/tutorial/index.ngdoc

@@ -9,7 +9,8 @@ the construction of an AngularJS web app. The app you will build is a catalog th
 of Android devices, lets you filter the list to see only devices that interest you, and then view
 details for any device.
 
-<img class="diagram" src="img/tutorial/catalog_screen.png" width="488" height="413">
+<img class="diagram" src="img/tutorial/catalog_screen.png" width="488" height="413" alt="demo
+application running in the browser">
 
 Work through the tutorial to see how Angular makes browsers smarter — without the use of extensions
 or plug-ins. As you work through the tutorial, you will:
@@ -57,63 +58,71 @@ and follow the instructions for setting up your computer.
   <div class="tab-pane well" id="git-mac" title="Git on Mac/Linux">
     <ol>
       <li><p>You'll need Git, which you can get from
-         <a href="http://git-scm.com/download">the Git site</a>.</p></li>
+         <a href="http://git-scm.com/download" title="Git site download">the Git site</a>.</p></li>
       <li><p>Clone the angular-phonecat repository located at
-      <a href="https://github.com/angular/angular-phonecat">Github</a> by running the following command:</p>
+      <a href="https://github.com/angular/angular-phonecat" title="Github Phonecat Repo">Github</a> by
+      running the following command:</p>
       <pre>git clone https://github.com/angular/angular-phonecat.git</pre>
-      <p>This command creates the <code>angular-phonecat</code> directory in your current
-directory.</p></li>
+      <p>This command creates the <code>angular-phonecat</code> directory in your current directory.</p></li>
       <li><p>Change your current directory to <code>angular-phonecat</code>:</p>
       <pre>cd angular-phonecat</pre>
-      <p>The tutorial instructions, from now on, assume you are running all commands from the <code>angular-phonecat</code>
-directory.</p></li>
+      <p>The tutorial instructions, from now on, assume you are running all commands from the
+      <code>angular-phonecat</code> directory.</p></li>
       <li><p>You will also need Node.js and Karma to run unit tests, so please verify that you have
-      <a href="http://nodejs.org/">Node.js</a> v0.10 or better installed
+      <a href="http://nodejs.org/" title="NodeJS org">Node.js</a> v0.10 or better installed
       and that the <code>node</code> executable is on your <code>PATH</code> by running the following
       command in a terminal window:</p></li>
       <pre>node --version</pre>
-      <p>Additionally install <a href="http://karma-runner.github.io/">Karma</a> and its plugins if you
-      don't have it already:</p>
+      <div class="alert alert-info">**Helpful note:** If you need to run a different version of
+      node.js in your local environment, consider installing
+      <a href="https://github.com/creationix/nvm" title="Node Version Manager Github Repo link">
+      Node Version Manager (nvm)</a>.</div>
+      <p>Additionally install <a href="http://karma-runner.github.io/" title="Karma site">Karma</a> and
+      its plugins if you don't have it already:</p>
       <pre>
       npm install
       </pre></li>
       <li><p>You will need an http server running on your system. Mac and Linux machines typically
-have Apache pre-installed, but If you don't already have one installed, you can use <code>node</code>
-to run a simple bundled http server: <code>node scripts/web-server.js</code>.</p></li>
+      have Apache pre-installed, but If you don't already have one installed, you can use <code>node</code>
+      to run <code>scripts/web-server.js</code>, a simple bundled http server.</p></li>
     </ol>
   </div>
 
   <div class="tab-pane well" id="git-win" title="Git on Windows">
     <ol>
       <li><p>You will need Node.js and Karma to run unit tests, so please verify that you have
-        <a href="http://nodejs.org/">Node.js</a> v0.10 or better installed
+        <a href="http://nodejs.org/" title="NodeJS site">Node.js</a> v0.10 or better installed
         and that the <code>node</code> executable is on your <code>PATH</code> by running the following
         command in a terminal window:</p>
         <pre>node --version</pre>
-        <p>Additionally install <a href="http://karma-runner.github.io/">Karma</a> if you
-           don't have it already:</p>
+        <div class="alert alert-info">**Helpful note:** If you need to run a different version of
+        node.js in your local environment, consider installing
+        <a href="https://github.com/creationix/nvm" title="Node Version Manager Github Repo link">
+        Node Version Manager (nvm)</a>.</div>
+        <p>Additionally install <a href="http://karma-runner.github.io/" title="Karma site">Karma</a>
+        if you don't have it already:</p>
         <pre>npm install -g karma</pre>
       </li>
       <li><p>You'll also need Git, which you can get from
-               <a href="http://git-scm.com/download">the Git site</a>.</p></li>
+               <a href="http://git-scm.com/download" title="Git site download">the Git site</a>.</p></li>
       <li><p>Clone the angular-phonecat repository located at <a
-      href="https://github.com/angular/angular-phonecat">Github</a> by running the following command:</p>
-      <pre>git clone https://github.com/angular/angular-phonecat.git</pre>
+      href="https://github.com/angular/angular-phonecat" "Github Angular-phonecat Repo">Github</a> by running
+      the following command:</p><pre>git clone https://github.com/angular/angular-phonecat.git</pre>
       <p>This command creates the <code>angular-phonecat</code> directory in your current directory.</p></li>
       <li><p>Change your current directory to <code>angular-phonecat</code>:</p>
       <pre>cd angular-phonecat</pre>
       <p>The tutorial instructions assume you are running all commands from the <code>angular-phonecat</code>
-directory.</p>
+      directory.</p>
       <p>You should run all <code>git</code> commands from Git bash.</p>
-      <p>Other commands like <code>test.bat</code> or <code>e2e-test.bat</code> should be
-executed from the Windows command line.</li>
-      <li><p>You need an http server running on your system, but if you don't already have one
-already installed, you can use <code>node</code> to run a simple
-bundled http server: <code>node scripts\web-server.js</code>.</p></li>
+      <p>Other commands like <code>test.bat</code> or <code>e2e-test.bat</code> should be executed from the
+      Windows command line.</li>
+      <li><p>You need an http server running on your system, but if you don't already have one already
+      installed, you can use <code>node</code> to run <code>scripts\web-server.js</code>, a simple bundled
+      http server.</p></li>
     </ol>
   </div>
 
-The last thing to do is to make sure your computer has a web browser and a good text editor
-installed. Now, let's get some cool stuff done!
+The last thing to do is to make sure your computer has a web browser and a good text editor installed. Now,
+let's get some cool stuff done!
 
-{@link step_00 <span class="btn btn-primary">Get Started!</span>}
+<a href="tutorial/step_00" title="Next Step"><span class="btn btn-primary">Get Started!</span></a>