An attempt to make clear how privilege escalation works with respect to the src/source host and dest/destination host. One existing note was incorporated into three new ones, iterating each.
In particular, if `rsync` is not installed on the remote machine the following error message will be encountered:
"rsync error: remote command not found"
This small change corrects behavior when one uses an .rsync-filter file to exclude some paths from both being transferred and being deleted, so that these excluded paths can be handled separately with different tasks (e.g. in order to deploy the excluded paths independently from the rest paths and notify handlers appropriately). The problem with the double -FF option is that it excludes the .rsync-filter file from being transferred to the receiver. However, deletions are done on the side of the receiver, so it is absolutely necessary the .rsync-filter file to be transferred to the receiver, so that the receiver knows what files to delete and what not to delete.
