tdf#45721 expresses confusion about how to remove a line created
by AutoCorrect "Apply Borders". This patch adds a <tip> about
how to do achieve that intention.
Change-Id: I381904eb53e24497bb38a8781f0f72cfb9cf8e8b
Reviewed-on: https://gerrit.libreoffice.org/c/help/+/110231
Tested-by: Jenkins
Reviewed-by: Seth Chaiklin <sdc.blanco@youmail.dk>