DOC: improve README

Author: jklymak

README.rst

@@ -16,6 +16,25 @@ installation.
 
 See the ``docs/conf.py`` file for other settings.
 
+There are three main templates that replace the defaults in ``pydata-sphinx-theme``:
+
+.. code-block::
+
+   navbar_start = mpl_navbar_logo.html
+   navbar_center = mpl_nav_bar.html
+   navbar_end = mpl_icon_links.html   
+
+Note that the option ``html_logo`` need not be specified as it is included 
+in ``mpl_sphinx_theme/mpl_navbar_logo.html``.  The logo is stored at 
+``mpl_sphinx_theme/static/images/logo2.svg``.  
+
+To change the top navbar, edit ``mpl_sphinx_theme/mpl_nav_bar.html``
+
+To change the social icons, edit ``mpl_sphinx_theme/mpl_icon_links.html``
+
+To change the style, edit ``mpl_sphinx_theme/static/css/style.css``
+
+
 Releasing
 ---------