docs(guide/concepts): spell "Angular" with cap "A", fix typos

In these two instances, Angular was spelled with a lower-case "a." All occurrences should be spelled
consistently.

Compound adjectives preceding the noun they modify should generally be hyphenated (cf Chicago Manual
of Style, 6.40), e.g., "so-called directives."

Closes #9896

docs/content/guide/concepts.ngdoc

@@ -56,10 +56,10 @@ Try out the Live Preview above, and then let's walk through the example and desc
 
 This looks like normal HTML, with some new markup. In Angular, a file like this is called a
 <a name="template">"{@link templates template}"</a>. When Angular starts your application, it parses and
-processes this new markup from the template using the so called <a name="compiler">"{@link compiler compiler}"</a>.
+processes this new markup from the template using the so-called <a name="compiler">"{@link compiler compiler}"</a>.
 The loaded, transformed and rendered DOM is then called the <a name="view">"view"</a>.
 
-The first kind of new markup are the so called <a name="directive">"{@link directive directives}"</a>.
+The first kind of new markup are the so-called <a name="directive">"{@link directive directives}"</a>.
 They apply special behavior to attributes or elements in the HTML. In the example above we use the
 {@link ng.directive:ngApp `ng-app`} attribute, which is linked to a directive that automatically
 initializes our application. Angular also defines a directive for the {@link ng.directive:input `input`}
@@ -89,7 +89,7 @@ A filter formats the value of an expression for display to the user.
 In the example above, the filter {@link ng.filter:currency `currency`} formats a number
 into an output that looks like money.
 
-The important thing in the example is that angular provides _live_ bindings:
+The important thing in the example is that Angular provides _live_ bindings:
 Whenever the input values change, the value of the expressions are automatically
 recalculated and the DOM is updated with their values.
 The concept behind this is <a name="databinding">"{@link databinding two-way data binding}"</a>.
@@ -150,13 +150,13 @@ different currencies and also pay the invoice.
 
 What changed?
 
-First, there is a new JavaScript file that contains a so called <a name="controller">"{@link controller controller}"</a>.
+First, there is a new JavaScript file that contains a so-called <a name="controller">"{@link controller controller}"</a>.
 More exactly, the file contains a constructor function that creates the actual controller instance.
 The purpose of controllers is to expose variables and functionality to expressions and directives.
 
 Besides the new file that contains the controller code we also added a
 {@link ng.directive:ngController `ng-controller`} directive to the HTML.
-This directive tells angular that the new `InvoiceController` is responsible for the element with the directive
+This directive tells Angular that the new `InvoiceController` is responsible for the element with the directive
 and all of the element's children.
 The syntax `InvoiceController as invoice` tells Angular to instantiate the controller
 and save it in the variable `invoice` in the current scope.
@@ -263,7 +263,7 @@ services, ...) is created and wired using dependency injection. Within Angular,
 the DI container is called the <a name="injector">"{@link di injector}"</a>.
 
 To use DI, there needs to be a place where all the things that should work together are registered.
-In Angular, this is the purpose of the so called <a name="module">"{@link module modules}"</a>.
+In Angular, this is the purpose of the so-called <a name="module">"{@link module modules}"</a>.
 When Angular starts, it will use the configuration of the module with the name defined by the `ng-app` directive,
 including the configuration of all modules that this module depends on.