[doc] add a user guide

doc/development-guide.rst

+===================================
+ Creating a New Database Interface
+===================================
+
+The best way to create a new database for |project| is by looking at examples.
+Name of database inteface packages for |project| usually start with ``bob.db.``.
+Take a look at our `satellite packages`_ list to find the available databases.
+
+.. include:: links.rst