Combine the "what's new" sessions to a single session

Squash "what's new in 2.12" and "what's new in 2.13" to a single
session, and also include preview of 2.14.

Change-Id: I72f06e2ac3d38e16cec2c3cb920870ee95b3d357
4 files changed
tree: ec81a70dbedc5941fd8a5731918cf84af8758234
  1. images/
  2. sessions/
  3. conduct-policy.md
  4. index.md
  5. navbar.md