[mkgmap-dev] Commit r4827: document that options --mdr7-del and mdr7-excl are case insensitive

Version mkgmap-r4827 was committed by gerd on Thu, 02 Dec 2021 document that options --mdr7-del and mdr7-excl are case insensitive http://www.mkgmap.org.uk/websvn/revision.php?repname=mkgmap&rev=4827