Fixes #7636: Add Katello Disconnected user guide.

The output looks different in the above scenario as well.  The following is what I observed:

```
# katello-disconnected export -t /var/tmp/export
Waiting for repos to finish publishing
Watching... (this may be safely interrupted with Ctrl+C)
State: waiting:
  repo: [rhel-6-server-optional-rpms-6_5-x86_64] packages remaining: [unknown]

State: waiting:
  repo: [rhel-6-server-optional-rpms-6_5-x86_64] packages remaining: [unknown]

State: waiting:
  repo: [rhel-6-server-optional-rpms-6_5-x86_64] packages remaining: [unknown]

State: waiting:
  repo: [rhel-6-server-optional-rpms-6_5-x86_64] packages remaining: [unknown]

State: finished:
  repo: [rhel-6-server-optional-rpms-6_5-x86_64] packages remaining: [unknown]


Watching finished
Done watching ...
 Archiving contents of /var/tmp/export into 4600M tar archives.
 NOTE: This may take a while.

Done exporting content, please copy /var/tmp/export/* to your disconnected host

```