docs: Add inheritance diagram to exceptions documentation

In light of exception hierarchy adjustments currently in progress
(I0e1e81b513fbbc7adb8bfaa1244993e345ab70d3) it becomes really helpful to
have inheritance diagram for exceptions in documentation.

Change-Id: Ie8f7b160de08fa8a91499cac2f94a76aff186e67
Merge "docs: Add inheritance diagram to exceptions documentation"