chore(docs): fix rendering of methods' this type

Author: gkalpak

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

@@ -17,7 +17,7 @@ <h4>Parameters</h4>
     {% endif %}
 
     {% if method.this %}
-    <h4>Method's {% code %}this{% endcode %}</h4>
+    <h4>Method's `this`</h4>
     {$ method.this | marked $}
     {% endif %}
 

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

@@ -1,4 +1,4 @@
 {% if doc.this %}
-<h3>Method's {% code %}this{% endcode %}</h3>
+<h3>Method's `this`</h3>
 {$ doc.this | marked $}
-{% endif %}
+{% endif %}