docs: update vault kms integration doc
docs: update vault kms integration doc

correct the name policy mentioned

Signed-off-by: Jiffin Tony Thottan <c5f636a65220e122633e16282ed0de93ac96a4fd@redhat.com>

rook/rook,rook/nfs,rook/nfs,rook/rook,rook/rook,rook/rook,rook/nfs,rook/rook