Move most of the documentation to .rst format

docs/commands/update.rst

@@ -0,0 +1,38 @@
+.. _update:
+
+Bash-it update
+^^^^^^^^^^^^^^
+
+To update Bash-it to the latest stable version, simply run:
+
+.. code-block:: bash
+
+   bash-it update stable
+
+If you want to update to the latest dev version (directly from master), run:
+
+.. code-block:: bash
+
+   bash-it update dev
+
+If you want to update automatically and unattended, you can add the optional
+``-s/--silent`` flag, for example:
+
+.. code-block:: bash
+
+   bash-it update dev --silent
+
+.. _migrate:
+
+Bash-it migrate
+^^^^^^^^^^^^^^^
+
+If you are using an older version of Bash-it, it's possible that some functionality has changed, or that the internal structure of how Bash-it organizes its functionality has been updated.
+For these cases, we provide a ``migrate`` command:
+
+.. code-block:: bash
+
+   bash-it migrate
+
+This command will automatically migrate the Bash-it structure to the latest version.
+The ``migrate`` command is run automatically if you run the ``update``\ , ``enable`` or ``disable`` commands.