Add most of the structure! plus several Base Layer docs

docs/base/config/syntax.rst

@@ -0,0 +1,59 @@
+
+.. highlight:: ini
+
+Config File Syntax
+==================
+
+Rattail config files follow the traditional `INI file`_ syntax, e.g. here is a
+snippet::
+
+   [rattail]
+   app_title = Poser
+
+.. _INI file: https://en.wikipedia.org/wiki/INI_file
+
+That example can be broken down into 3 parts:
+
+* section (the name in square brackets, "rattail")
+* option (the name of the setting being defined, "app_title")
+* value (the value for the setting, "Poser")
+
+When logic within the app needs to retrieve a value from config, it does so by
+requesting both the section and option by name, for example:
+
+.. code-block:: python
+
+   config.get('rattail', 'app_title')   # returns "Poser"
+
+Under the hood we use Python's `configparser`_ module to parse config files.
+
+.. _configparser: https://docs.python.org/3/library/configparser.html
+
+If you think it would be handy for your app to have a new setting for some
+reason, just create one and use it like so::
+
+   [poser]
+   foo = bar
+
+.. code-block:: python
+
+   config.get('poser', 'foo')   # returns "bar"
+
+So far our examples have been for simple string values.  There is no way within
+the standard INI file syntax, to define any data types other than string.
+However the Rattail config parser/object can "coerce" values to a given type if
+so requested, for example::
+
+   [poser]
+   foo_flag = true
+   foo_number = 42
+   foo_entries =
+       first
+       second
+       third
+
+.. code-block:: python
+
+   config.getbool('poser', 'foo_flag')      # returns True
+   config.getint('poser', 'foo_number')     # returns 42
+   config.getlist('poser', 'foo_entries')   # returns ["first", "second", "third"]