- Docs: Add note about not cloning recursively

README.md

@@ -50,6 +50,12 @@ For testing the latest version in `master`, you may use
 ### Quick install
 
 1. Clone or copy the repository contents (at least the `editor` directory).
+    Please note that you should not do a recursive Git clone (i.e., with the
+    `--recurse` or `--recurse-submodules` flags), as you will get assorted
+    past versions (which are available on the parent as branches anyways).
+    (The reason these past versions are available as submodules is merely
+    for convenience in hosting these versions, along with `master`, online
+    on Github Pages.)
 1. If you need programmatic customization, see its section below.
 1. Otherwise, just add an iframe to your site, adding any extensions or
   configuration (see `docs/tutorials/ConfigOptions.md`