Update comments

Signed-off-by: John Else <john.else@citrix.com>
CP-5924: Add a function to help with PGPU capacity tracking

Signed-off-by: John Else <john.else@citrix.com>
CP-5924: Implement GPU_group.get_remaining_capacity

Signed-off-by: John Else <john.else@citrix.com>
CP-5924: Add GPU_group.get_remaining_capacity to CLI

Signed-off-by: John Else <john.else@citrix.com>
Merge pull request #1435 from johnelse/cp-5924

Implement GPU_group.get_remaining_capacity