Description of problem:

Now that unit removal is supported for synced repos as well, the cli help should generalize it as well.

[root@hp-dl380pgen8-02-vm-1 ~]# pulp-admin rpm repo 
Usage: pulp-admin [SUB_SECTION, ..] COMMAND
Description: repository lifecycle commands

Available Sections:
  
  remove  - remove copied or uploaded modules from a repository


[root@hp-dl380pgen8-02-vm-1 ~]# pulp-admin iso repo 
Usage: pulp-admin [SUB_SECTION, ..] COMMAND
Description: repository lifecycle commands

Available Sections:
  publish - run publish tasks
  sync    - run or schedule sync tasks
  uploads - upload ISOs into a repository

Available Commands:
  remove - remove copied or uploaded units from a repository
  update - changes metadata on an existing repository


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