fix(*): fix PUG syntax errors (#3401)

These errors are being missed by the Jade parser
but the more stringent Pug parser treats them as
errors.

public/docs/ts/latest/guide/dependency-injection.jade

@@ -361,7 +361,7 @@ a#prep-for-injection
     Angular injector to inject an instance of
     `HeroService` whenever it creates a new `HeroListComponent`.
 
-#di-metadata
+a#di-metadata
 :marked
   ### Implicit injector creation
 
@@ -382,7 +382,7 @@ a#prep-for-injection
   or after navigating to a component with the [router](./router.html).
   If you let Angular do its job, you'll enjoy the benefits of automated dependency injection.
 
-a:#singleton-services
+a#singleton-services
 :marked
   ### Singleton services
 

public/docs/ts/latest/guide/pipes.jade

@@ -458,7 +458,7 @@ a(id="no-filter-pipe")
 
   The minification hazard is also compelling, if less obvious. Imagine a sorting pipe applied to a list of heroes.
   The list might be sorted by hero `name` and `planet` of origin properties in the following way:
-code-example(language="html")
+code-example(language="html").
   <!-- NOT REAL CODE! -->
   <div *ngFor="let hero of heroes | orderBy:'name,planet'"></div>
 :marked

public/docs/ts/latest/guide/typescript-configuration.jade

@@ -87,7 +87,7 @@ a(id="typings")
   Since the QuickStart is targeting `es5`, you can override the
   list of declaration files to be included:
 
-code-example(format=".")
+code-example(format=".").
   "lib": ["es2015", "dom"]
 
 :marked