Document the project philosophy.

documentation/about.rst

@@ -9,6 +9,36 @@ About Betty
 
    about/*
 
+Philosphy
+---------
+
+Storytelling
+^^^^^^^^^^^^
+Betty builds sites that tell a story. Raw family data is visualized in different, sometimes interactive ways.
+Additional information is added automatically from a variety of third-party sources, augmenting your family trees
+with further encyclopedic information, imagery, and maps.
+
+Simplicity
+^^^^^^^^^^
+Anyone who can download and install a desktop application should be able to generate a site and view it.
+We aim for Betty to be simple to use, out of the box, for everyone.
+
+Speed
+^^^^^
+Betty sites are fast. Faster than most other sites we use on a daily basis.
+
+Security and maintenance
+^^^^^^^^^^^^^^^^^^^^^^^^
+A Betty site is secure and requires almost no maintenance.
+
+.. note::
+    This is about generated sites. You are still advised to install updates to your installation of Betty when they become available.
+
+What is Betty not?
+^^^^^^^^^^^^^^^^^^
+Betty does not help you gather or manage the data for your family history. For that purpose, use a product such as
+`Gramps <https://gramps-project.org>`_, or a service like `Ancestry.com <https://www.ancestry.com>`_.
+
 Find Betty on
 -------------
 - :fab:`twitter` `Twitter <https://twitter.com/Betty_Project>`_