Title: dead links in history

Description:

Check https://www.envoyproxy.io/docs/envoy/latest/version_history/v1.11.0:

• Use of json based schema in router check tool tests. The tests should follow validation schema.
• tools: added proto support for router check tool tests.

The links linked to v1.11:test are all dead, and can not find v1.11 branch in GH page. Is it deleted?

It is just a history issue, with little effect on users. While these kinds of problems should be avoided as much as possible as the version iterates.