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

Closes #4816

modules/angular2/src/core/pipes/async_pipe.ts

@@ -40,7 +40,7 @@ var _observableStrategy = new ObservableStrategy();
  * emitted.
  * When a new value is emitted, the `async` pipe marks the component to be checked for changes.
  *
- * # Example
+ * ### Example
  * The example below binds the `time` Observable to the view. Every 500ms, the `time` Observable
  * updates the view with the current time.
  *

modules/angular2/src/core/pipes/date_pipe.ts

@@ -26,7 +26,7 @@ var defaultLocale: string = 'en-US';
  *
  * Formats a date value to a string based on the requested format.
  *
- * # Usage
+ *##Usage
  *
  *     expression | date[:format]
  *
@@ -67,7 +67,7 @@ var defaultLocale: string = 'en-US';
  *
  * Timezone of the formatted text will be the local system timezone of the end-users machine.
  *
- * # Examples
+ * ### Examples
  *
  * Assuming `dateObj` is (year: 2015, month: 6, day: 15, hour: 21, minute: 43, second: 11)
  * in the _local_ time and locale is 'en-US':

modules/angular2/src/core/pipes/json_pipe.ts

@@ -6,7 +6,7 @@ import {Pipe} from 'angular2/src/core/metadata';
 /**
  * Implements json transforms to any object.
  *
- * # Example
+ * ### Example
  *
  * In this example we transform the user object to json.
  *

modules/angular2/src/core/pipes/lowercase_pipe.ts

@@ -8,7 +8,7 @@ import {InvalidPipeArgumentException} from './invalid_pipe_argument_exception';
 /**
  * Implements lowercase transforms to text.
  *
- * # Example
+ * ### Example
  *
  * In this example we transform the user text lowercase.
  *

modules/angular2/src/core/pipes/number_pipe.ts

@@ -62,7 +62,7 @@ export class NumberPipe {
  * Formats a number as local text. i.e. group sizing and separator and other locale-specific
  * configurations are based on the active locale.
  *
- * # Usage
+ *##Usage
  *
  *     expression | number[:digitInfo]
  *
@@ -77,7 +77,7 @@ export class NumberPipe {
  * For more information on the acceptable range for each of these numbers and other
  * details see your native internationalization library.
  *
- * # Examples
+ * ### Examples
  *
  *     {{ 123 | number }}              // output is 123
  *     {{ 123.1 | number: '.2-3' }}    // output is 123.10
@@ -99,7 +99,7 @@ export class DecimalPipe extends NumberPipe implements PipeTransform {
  *
  * Formats a number as local percent.
  *
- * # Usage
+ *##Usage
  *
  *     expression | percent[:digitInfo]
  *
@@ -121,7 +121,7 @@ export class PercentPipe extends NumberPipe implements PipeTransform {
  *
  * Formats a number as local currency.
  *
- * # Usage
+ *##Usage
  *
  *     expression | currency[:currencyCode[:symbolDisplay[:digitInfo]]]
  *

modules/angular2/src/core/pipes/slice_pipe.ts

@@ -16,7 +16,7 @@ import {Pipe} from '../metadata';
  *
  * The ending index of the subset to return is specified by the optional `end` parameter.
  *
- * # Usage
+ *##Usage
  *
  *     expression | slice:start[:end]
  *
@@ -44,7 +44,7 @@ import {Pipe} from '../metadata';
  * When operating on a [List], the returned list is always a copy even when all
  * the elements are being returned.
  *
- * # Examples
+ * ### Examples
  *
  * ## List Example
  *

modules/angular2/src/core/pipes/uppercase_pipe.ts

@@ -7,7 +7,7 @@ import {InvalidPipeArgumentException} from './invalid_pipe_argument_exception';
 /**
  * Implements uppercase transforms to text.
  *
- * # Example
+ * ### Example
  *
  * In this example we transform the user text uppercase.
  *