chore(doc-gen): improve headings for events and examples

The "Events" heading now gets an id (which makes them show in
the table of contents, and their "Parameters" use a heading with
a lower priority (previously it was the same as "Events" itself).

The "@example" tag now generates the heading "Example" if there's
only one, or "Examples" if there are multiple.

docs/config/templates/ngdoc/api/api.template.html

@@ -52,7 +52,7 @@
 
   {% block examples %}
   {%- if doc.examples %}
-  <h2 id="example">Examples</h2>
+  <h2 id="examples">{$ "Examples" if doc.examples | length > 1 else "Example" $}</h2>
   {%- for example in doc.examples -%}
     {$ example | marked $}
   {%- endfor -%}

docs/config/templates/ngdoc/lib/events.template.html

@@ -2,11 +2,11 @@
 {% import "lib/deprecated.html" as x -%}
 
 {%- if doc.events %}
-<h2>Events</h2>
+<h2 id="events">Events</h2>
 <ul class="events">
   {%- for event in doc.events %}
   <li id="{$ event.name $}">
-    <h3>{$ event.name $}</h3>
+    <h3 id="event-{$ event.name $}">{$ event.name $}</h3>
     <div>{$ event.description | marked $}</div>
 
     {$ x.deprecatedBlock(event) $}
@@ -27,7 +27,7 @@
     {% endif -%}
     {%- if event.params %}
     <section class="api-section">
-      <h3>Parameters</h3>
+      <h4>Parameters</h4>
       {$ lib.paramTable(event.params) $}
     </section>
     {%- endif -%}

docs/config/templates/ngdoc/lib/methods.template.html

@@ -27,7 +27,7 @@
     {% endif %}
 
     {%- if method.examples %}
-    <h4 id="{$ doc.name $}.{$ method.name $}-examples">Examples</h4>
+    <h4 id="{$ doc.name $}.{$ method.name $}-examples">{$ "Examples" if method.examples | length > 1 else "Example" $}</h4>
     {%- for example in method.examples -%}
       {$ example | marked $}
     {%- endfor -%}