Update README.md
Specify a more generalizable use of `git submodule deinit`
@@ -105,7 +105,7 @@ For developers who will be working on Blocky within the context of App Inventor,
If you need to switch back to a branch that does contains the Blockly and Closure Library sources in the tree, you will need to run the command:
- $ git submodule deinit .
+ $ git submodule deinit --all
to clear out the submodules ___before switching branches___. When switching back, you will need to repeat the initialization and update procedure above.
