Documented --bootstrap

Author: inclement

doc/source/commands.rst

@@ -73,6 +73,14 @@ supply those that you need.
 ``--arch``
   The architecture to build for. Currently only one architecture can be 
   targeted at a time, and a given distribution can only include one architecture.
+  
+``--bootstrap BOOTSTRAP``
+
+  The Java bootstrap to use for your application. You mostly don't
+  need to worry about this or set it manually, as an appropriate
+  bootstrap will be chosen from your ``--requirements``. Current
+  choices are ``sdl2`` or ``pygame``; ``sdl2`` is experimental but
+  preferable where possible.
 
 
 .. note:: These options are preliminary. Others will include toggles