Hold and release permissions exist

The man page was missing these two permissions.
Add the missing permissions to the man page. 

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Jeremy Faulkner <gldisater@gldis.ca>
Closes openzfs#11727

man/man8/zfs-allow.8

@@ -205,6 +205,7 @@ diff             subcommand     Allows lookup of paths within a dataset
                                 given an object number, and the ability
                                 to create snapshots necessary to
                                 'zfs diff'.
+hold             subcommand     Allows adding a user hold to a snapshot
 load-key         subcommand     Allows loading and unloading of encryption key
                                 (see 'zfs load-key' and 'zfs unload-key').
 change-key       subcommand     Allows changing an encryption key via
@@ -214,6 +215,8 @@ promote          subcommand     Must also have the 'mount' and 'promote'
                                 ability in the origin file system
 receive          subcommand     Must also have the 'mount' and 'create'
                                 ability
+release          subcommand     Allows releasing a user hold which might
+                                destroy the snapshot
 rename           subcommand     Must also have the 'mount' and 'create'
                                 ability in the new parent
 rollback         subcommand     Must also have the 'mount' ability