[BUGFIX] Replace EAB with Board in readme

Updates to the Final notes section:

* The Expert Advisory Board (EAB), which no longer exists, has been
  replaced with the TYPO3 Association Board, which does exist and has
  absorbed the functions of the EAB.

* Adds a link to information about the TYPO3 Association

* Reformats the "Donate to TYPO3" and "Become a member of the TYPO3
  Association" links.

* Explicitly links "Become a member of the TYPO3 Association" to the
  page listing membership options.

Resolves: #100217
Releases: main, 11.5, 10.4
Change-Id: I05ad4bf263fe93e62fc50e8f9f9af7e6387d85d8
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/78062


Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Benni Mack <benni@typo3.org>