Rename docs for contrib modules

docs/reference/contrib/api/installation.rst

@@ -1,5 +1,5 @@
-Installing Wagtail API
-======================
+Wagtail API Installation
+========================
 
 
 To install, add ``wagtail.contrib.wagtailapi`` to ``INSTALLED_APPS`` in your Django settings and configure a URL for it in ``urls.py``

docs/reference/contrib/api/usage.rst

@@ -1,4 +1,4 @@
-Wagtail API usage guide
+Wagtail API Usage Guide
 =======================
 
 Listing views

docs/reference/contrib/frontendcache.rst

@@ -1,7 +1,7 @@
 .. _frontend_cache_purging:
 
-Frontend cache invalidation
-===========================
+Frontend cache invalidator
+==========================
 
 .. versionchanged:: 0.7
 

docs/reference/contrib/sitemaps.rst

@@ -1,7 +1,7 @@
 .. _sitemap_generation:
 
-Sitemap generation
-==================
+Sitemap generator
+=================
 
 This document describes how to create XML sitemaps for your Wagtail website using the ``wagtail.contrib.wagtailsitemaps`` module.
 

docs/reference/contrib/staticsitegen.rst

@@ -1,5 +1,5 @@
-Generating a static site
-========================
+Static site generator
+=====================
 
 This document describes how to render your Wagtail site into static HTML files on your local file system, Amazon S3 or Google App Engine, using `django medusa`_ and the ``wagtail.contrib.wagtailmedusa`` module.