Add section headers to the customization chapter

docs/topics/customization.rst

@@ -5,6 +5,9 @@ Customization
 The general appearance of **Mayan EDMS** can be customized entirely just
 by changing a few settings.
 
+------
+Themes
+------
 **Mayan EDMS** uses `Andrea Franz's excellent web app template`_ which includes
 several themes that could be used to adapt **Mayan EDMS**'s appearance to match
 an organtization existing applications' look and feel.
@@ -15,6 +18,9 @@ configuration option to one of its valid values.
 .. image:: themes.png
  :alt: themes
 
+------------
+Login screen
+------------
 The amount of information presented at the login screen can also be restricted
 if for security or desgin reasons using :setting:`WEB_THEME_VERBOSE_LOGIN`
 configuration option.
@@ -22,11 +28,17 @@ configuration option.
 .. image:: mayan-login.png
  :alt: mayan login screen
 
+-----------
+Home screen
+-----------
 Sometimes users just want to go directly to work and not just be greeted with
 a home screen, for these kind of situations **Mayan EDMS** has the
 :setting:`MAIN_DISABLE_HOME_VIEW` configuration option which will cause
 users to land on their ``recent document list`` as soon as they log in.
 
+-----
+Icons
+-----
 Some themes such as ``default`` might be more visually appealing to some
 people without the menu icons, for this **Mayan EDMS** provides the
 :setting:`MAIN_DISABLE_ICONS` configuration option.