Start collecting documentation, and add an in-tree glossary. Encourage new contributors to add missing entries as appropriate.

CONTRIBUTING.md

@@ -17,9 +17,12 @@ the GitHub issue that you want to work on it. This is to prevent duplicated
 efforts from contributors on the same issue.
 
 Head over to [Servo Starters](http://servo.github.io/servo-starters/) to find
-good tasks to start with.
+good tasks to start with. If you come across words or jargon that do not make
+sense, please check [the glossary](docs/glossary.md) first. If there's no
+matching entry, please make a pull request to add one with the content `TODO`
+so we can correct that!
 
-See [`HACKING_QUICKSTART.md`](HACKING_QUICKSTART.md) for more information
+See [`HACKING_QUICKSTART.md`](docs/HACKING_QUICKSTART.md) for more information
 on how to start working on Servo.
 
 ## Pull Request Checklist
@@ -31,9 +34,6 @@ on how to start working on Servo.
 - Commits should be as small as possible, while ensuring that each commit is
   correct independently (i.e., each commit should compile and pass tests). 
 
-- Don't put submodule updates in your pull request unless they are to landed
-  commits.
-
 - If your patch is not getting reviewed or you need a specific person to review
   it, you can @-reply a reviewer asking for a review in the pull request or a
   comment, or you can ask for a review in `#servo` on `irc.mozilla.org`.