Add draft release notes for RBTools 3.0.
This change adds release notes for the new features and improvements
that will ship as RBTools 3.0.
Testing Done:
Built HTML and checked output.
Reviewed at
RBTools Release Notes
=====================
+3.0 Releases
+============
+
+.. toctree::
+ :maxdepth: 1
+
+ 3.0
+
+
2.0 Releases
============
