[TASK] Update phpdoc of pi_getPageLink/pi_linkToPage

Calls methods in contentObjectRenderer and thus
should match that phpdoc over there (especially
giving a hint about what to urlencode and what not).

Resolves: #48316
Releases: 6.2
Change-Id: Id932763dc06ffaad09f169aff9ac9457d890a777
Reviewed-on: https://review.typo3.org/20856
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters