Enable %B (barcode) and %C (catalog number) template variables

Already included but were not allowed.
Improved documentation.

Signed-off-by: JoeLametta <JoeLametta@users.noreply.github.com>

man/whipper-cd-rip.rst

@@ -94,6 +94,8 @@ Template schemes
 
 | - %A: release artist
 | - %S: release sort name
+| - %B: release barcode
+| - %C: release catalog number
 | - %d: disc title
 | - %y: release year
 | - %r: release type, lowercase