[DOCS] Improve bin/typo3 cache:flush description

There is no word 'postparation' according to native speaker Sarah McCarthy.

And also the sentence was hard to understand for non-native speakers.

The command is not only useful during deployment so we mention other usecases.

Resolves: #103857
Releases: main, 12.4
Change-Id: I602d8fe70ccbe6831278669fb2078318be4bcf63
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/84312


Reviewed-by: Chris Müller <typo3@brotkrueml.dev>
Tested-by: Benjamin Franzke <ben@bnf.dev>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Chris Müller <typo3@brotkrueml.dev>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Benjamin Franzke <ben@bnf.dev>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>