[TASK] Remove comment from .gitignore file

There is a comment in the .gitignore file to report any changes
to this file into a Forge issue. Till now nobody did that.
Remove this useless comment now.

Resolves: #76510
Releases: master
Change-Id: If5dc0193c85f904fd7a038ee9cf6ceb4c98661da
Reviewed-on: https://review.typo3.org/48494


Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>
Reviewed-by: Morton Jonuschat <m.jonuschat@mojocode.de>
Tested-by: Morton Jonuschat <m.jonuschat@mojocode.de>