README.md: Updates and Fixes

README.md: Updates and Fixes

* Outdated information has been removed.
* New links added.
* Placeholder added for link to change logs.

Going forward, the release process will create HTML versions of the README
and change log and will update the link in the README to the current
change log for the branch...

* In the development branches, the link will always point to the current
  release on GitHub.
* In the "releases/*" branches and the tarballs, the link will point to the
  ChangeLogs/ChangeLog-<version>.html file in the source directory.
* On the downloads website, the link will point to the
  ChangeLog-<version>.html file in the same directory.

Resolves: #1131
(cherry picked from commit 9f4b52bf2b4ae5aa71fd942b132084be8a397ecb)