docs: add some narrative docs to explain basic concepts

still needs a lot of work i'm sure..gotta start somewhere

docs/narr/cli/builtin.rst

@@ -0,0 +1,27 @@
+
+===================
+ Built-in Commands
+===================
+
+Below are the :term:`subcommands <subcommand>` which come with
+WuttaSync.
+
+It is fairly simple to add more; see :doc:`custom`.
+
+
+.. _wutta-import-csv:
+
+``wutta import-csv``
+--------------------
+
+Import data from CSV file(s) to the Wutta :term:`app database`.
+
+This *should* be able to automatically target any table mapped in the
+:term:`app model`.  The only caveat is that it is "dumb" and does not
+have any special field handling.  This means the column headers in the
+CSV file must be named the same as in the target table, and some data
+types may not behave as expected etc.
+
+Defined in: :mod:`wuttasync.cli.import_csv`
+
+.. program-output:: wutta import-csv --help