fix typo in docs

...and removed one repetative "the"

Author: Philzen

demo/withPlugins/withFixedHeader.html

@@ -4,18 +4,18 @@ <h1><i class="fa fa-play"></i>&nbsp;With the DataTables <a href="https://datatab
     </header>
     <section class="article-content">
         <p>
-            The <code>angular-datatables</code> also provides an API in order to make the plugin <code>FixedHeader</code> works with datatables.
+            The <code>angular-datatables</code> also provides an API in order to make the plugin <code>FixedHeader</code> work with datatables.
         </p>
         <p>
-            You need to add the files <code>angular-datatables.fixedheader.min.js</code> to your HTML file.
+            You need to add the file <code>angular-datatables.fixedheader.min.js</code> to your HTML file.
         </p>
         <p>
             You also need to add the dependency <code>datatables.fixedheader</code> to your Angular app.
         </p>
         <div class="api alert alert-danger">
             <p>
-                <i class="fa fa-warning"></i>&nbsp;Beware when using routers. It seems that the header and the footer stay
-                in your DOM even when you change your application state. So you will need to tweek your code to remove them
+                <i class="fa fa-warning"></i>&nbsp;Beware when using routers. It seems that the header and footer stay
+                in your DOM even when you change your application state. So you will need to tweak your code to remove them
                 when exiting the state.
             </p>
             <p>