docs(chore): make styles consistent for API doc headings

Closes #4816

modules/angular2/src/http/backends/mock_backend.ts

@@ -43,7 +43,7 @@ export class MockConnection implements Connection {
    * Sends a mock response to the connection. This response is the value that is emitted to the
    * {@link EventEmitter} returned by {@link Http}.
    *
-   * #Example
+   * ### Example
    *
    * ```
    * var connection;
@@ -94,7 +94,7 @@ export class MockConnection implements Connection {
  * This class can be injected in tests, and should be used to override providers
  * to other backends, such as {@link XHRBackend}.
  *
- * #Example
+ * ### Example
  *
  * ```
  * import {MockBackend, DefaultOptions, Http} from 'angular2/http';
@@ -126,7 +126,7 @@ export class MockBackend implements ConnectionBackend {
    * of {@link MockConnection} instances that have been created by this backend. Can be subscribed
    * to in order to respond to connections.
    *
-   * #Example
+   * ### Example
    *
    * ```
    * import {MockBackend, Http, BaseRequestOptions} from 'angular2/http';

modules/angular2/src/http/backends/xhr_backend.ts

@@ -88,7 +88,7 @@ export class XHRConnection implements Connection {
  * overridden if a different backend implementation should be used,
  * such as in a node backend.
  *
- * #Example
+ * ### Example
  *
  * ```
  * import {Http, MyNodeBackend, HTTP_PROVIDERS, BaseRequestOptions} from 'angular2/http';

modules/angular2/src/http/base_request_options.ts

@@ -72,7 +72,7 @@ export class RequestOptions {
    * the `options` object. If these values should be merged, it should be done prior to calling
    * `merge` on the `RequestOptions` instance.
    *
-   * Example ([live demo](http://plnkr.co/edit/6w8XA8YTkDRcPYpdB9dk?p=preview))
+   * ### Example ([live demo](http://plnkr.co/edit/6w8XA8YTkDRcPYpdB9dk?p=preview))
    *
    * ```typescript
    * import {RequestOptions, Request, RequestMethods} from 'angular2/http';

modules/angular2/src/http/base_response_options.ts

@@ -72,7 +72,7 @@ export class ResponseOptions {
    * This may be useful when sharing a base `ResponseOptions` object inside tests,
    * where certain properties may change from test to test.
    *
-   * Example ([live demo](http://plnkr.co/edit/1lXquqFfgduTFBWjNoRE?p=preview))
+   * ### Example ([live demo](http://plnkr.co/edit/1lXquqFfgduTFBWjNoRE?p=preview))
    *
    * ```typescript
    * import {ResponseOptions, Response} from 'angular2/http';

modules/angular2/src/http/http.ts

@@ -36,7 +36,7 @@ function mergeOptions(defaultOpts, providedOpts, method, url): RequestOptions {
  * `request` returns an {@link Observable} which will emit a single {@link Response} when a
  * response is received.
  *
- * #Example
+ * ### Example
  *
  * ```typescript
  * import {Http, HTTP_PROVIDERS} from 'angular2/http';
@@ -58,7 +58,7 @@ function mergeOptions(defaultOpts, providedOpts, method, url): RequestOptions {
  * ```
  *
  *
- * #Example
+ * ### Example
  *
  * ```
  * http.get('people.json').observer({next: (value) => this.people = people});
@@ -68,7 +68,7 @@ function mergeOptions(defaultOpts, providedOpts, method, url): RequestOptions {
  * {@link XHRBackend} in this case), which could be mocked with dependency injection by replacing
  * the {@link XHRBackend} provider, as in the following example:
  *
- * #Example
+ * ### Example
  *
  * ```typescript
  * import {MockBackend, BaseRequestOptions, Http} from 'angular2/http';

modules/angular2/src/http/static_response.ts

@@ -12,7 +12,7 @@ import {isJsObject} from './http_utils';
  * usually instantiated by end-users, it is the primary object interacted with when it comes time to
  * add data to a view.
  *
- * #Example
+ * ### Example
  *
  * ```
  * http.request('my-friends.txt').subscribe(response => this.friends = response.text());