Add information about config.debug (X-TYPO3-Debug-Cache)

[sypets]

https://docs.typo3.org/m/typo3/reference-typoscript/main/en-us/Setup/Config/Index.html#debug

• missing information about X-TYPO3-Debug-Cache (currently, only mentions X-TYPO3-Parsetime).

Apparently, if page is is served from cache, the X-TYPO3-Debug-Cache header is sent. If page is generated (not served from cache), the header is not sent.

• when these headers are sent and how they can be used (e.g. when page is loaded from cache vs. not loaded from cache)
• possibly refer to admin panel where further analysis is possible

Related

• https://forge.typo3.org/issues/98126
• typo3/sysext/frontend/Classes/Controller/TypoScriptFrontendController.php
• typo3/sysext/frontend/Classes/Middleware/TimeTrackerInitialization.php
• typo3/sysext/core/Documentation/Changelog/9.0/Feature-82419-SendFrontendDebugInformationAsHTTPResponseHeader.rst
• typo3/sysext/core/Documentation/Changelog/11.0/Feature-92334-X-Redirect-ByHeaderForPagesWithRedirectTypes.rst