Change in playbook usage: don't copy playbook into work directory

[mbukatov]

Right now, README states that:

If you use tendrl-ansible from rpm package, copy site.yml playbook into working directory
(where you already store the inventory file):

$ cp /usr/share/doc/tendrl-ansible-VERSION/site.yml .

We should probably change this to symlinking instead.

[dahorak]

@mbukatov wouldn't be sufficient to run the site.yml playbook directly from the original location in /usr/share/doc/...?

[mbukatov]

That would work as well. That said, that such symlink can be useful eg. when trying to recall which playbook I used some with the inventory file time ago. But maybe it's not worth it.