cbbackupmgr, need examples for --filter-keys and --filter-values

https://docs.couchbase.com/server/6.5/backup-restore/cbbackupmgr-restore.html

Some of the newer flags (like --filter-keys and --filter-values) are missing from the command synopsis, in documentation for 6.5 as well as previous versions.

Samples that show how the arguments should look like for each of the flags would be very helpful. We mention it should be a regular expression for --filter-keys and --filter-values, but regular expressions come in a variety of syntaxes.

Reporter: Oleg Kuzmin
E-mail: oleg.kuzmin@couchbase.com