Revert "Remove documentation of obsolete gerrit.canLoadInIFrame"
Revert "Remove documentation of obsolete gerrit.canLoadInIFrame"

This reverts commit 21d22133a1232cd71bb8fc8dcb6f806f62afee68.

Reason for revert: gerrit.canLoadInIFrame is needed for Issue 12926

Change-Id: Ie7332415751496ab0f1f9b6d7ca72c05bb881903

GerritCodeReview/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit