doc: mention creating application support bitcoin folder on OSX
doc: mention creating application support bitcoin folder on OSX

Github-Pull: #15802
Rebased-From: 8dfbb5cf236cb70a2a1e65b076ccb7e2901833bd

chaincoin/chaincoin,chaincoin/chaincoin,chaincoin/chaincoin,chaincoin/chaincoin,chaincoin/chaincoin,chaincoin/chaincoin