docs: fix usage of autodata

Should really be autoattribute, since we're referring to a
class attribute. This fixes a documentation build error.

Signed-off-by: Cleber Rosa <crosa@redhat.com>
client/shared/distro.py: fix references to CHECK_FILE

Signed-off-by: Cleber Rosa <crosa@redhat.com>
frontend/tko/models.py: document the TestView model

As it is referenced by many TKO rpc services and cross references
makes things much easier to understand.

Signed-off-by: Cleber Rosa <crosa@redhat.com>
tko: document the functionality exported via RPC

This has a couble of goals:

   1) enable the easier consumption of the TKO information
   2) expand the TKO support in ARC
   3) fix 4 unittest bugs in the TKO rpc interface
   4) implement a method that diffs the results of two (similar)
      tests.

Signed-off-by: Cleber Rosa <crosa@redhat.com>