Add Tasks section to TODO.md

TODO.md

@@ -5,6 +5,10 @@
 * Where should we store deprecated documentation? Should we include it at all?
 * Should we rename `develop.md` (`core/develop.md` vs `extension/develop.md`?)
 
+## Tasks
+
+* Finish importing [GitHub for CiviCRM](https://wiki.civicrm.org/confluence/display/CRMDOC43/GitHub+for+CiviCRM) to `develop.md` and `develop-deprecated.md`.
+
 ## Extension questions
 
 * How do I include Composer libraries in my CiviCRM extension?