[TASK] Improve TCA description of sys_template record fields

Some of the more advanced fields of sys_template records
are rather hard to understand without additional description.

The patch uses the TCA "description" feature to add some
explanations and hints if and when integrators should bother
with them in typical scenarios.

Resolves: #98017
Related: #97816
Releases: main, 11.5
Change-Id: Ifb4166dd225ec1c74339726f97ec7d7391e6996e
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/75282


Tested-by: core-ci <typo3@b13.com>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>