docs(guide/Conceptual Overview): add missing object in sentence

docs: minor grammar fix
missing word in overview

Closes angular#13346

Author: aperala

docs/content/guide/concepts.ngdoc

@@ -76,7 +76,7 @@ stores/updates the value of the input field into/from a variable.
 The second kind of new markup are the double curly braces `{{ expression | filter }}`:
 When the compiler encounters this markup, it will replace it with the evaluated value of the markup.
 An <a name="expression">{@link expression expression}</a> in a template is a JavaScript-like code snippet that allows
-to read and write variables. Note that those variables are not global variables.
+Angular to read and write variables. Note that those variables are not global variables.
 Just like variables in a JavaScript function live in a scope,
 Angular provides a <a name="scope">{@link scope scope}</a> for the variables accessible to expressions.
 The values that are stored in variables on the scope are referred to as the <a name="model"></a>*model*