Merge pull request duilio#87 from MrSenko/issue56_readme

Add docs for Disqus and note about comments rendering. Fixes duilio#56

README.rst

@@ -95,6 +95,14 @@ FeedBurner integration
   you've set the ``FEED_RSS`` or ``FEED_ATOM`` variables. This way, you can arbitrarily set your generated feed URL while
   presenting your FeedBurner URL to your users.
 
+Disqus comments
+---------------
+
+- ``DISQUS_SITENAME``: (required to enable) set this to the short site identifier
+  of your Disqus site. Example:
+  ``mrsenko``
+
+
 Isso self-hosted comments
 -------------------------
 
@@ -106,6 +114,10 @@ website.
   is being served from without a trailing slash. Example:
   ``http://example.com``
 
+**NOTE:** comments are displayed only if the article is not a draft and
+``SITEURL`` is defined (usually is) and either one of ``DISQUS_SITENAME`` or
+``ISSO_SITEURL`` are defined!
+
 X min read
 ----------