docs(mte2): update docs

Add a section under release for capturing and populating
build options that are deprecated and removed.

Various fixes and refactor[1] led to removal of certain MTE
build options so capture this part in build-options docs.

[1]: https://review.trustedfirmware.org/q/topic:%22mte_fixes%22

Change-Id: I74a82f6f73f7f1dceea65a295ad2df60301ad838
Signed-off-by: Govindraj Raja <govindraj.raja@arm.com>
1 file changed