Change how salt-ssh connects with sshpass.

When the 'passwd' option is set in the rooster file for a host, then salt won't use PubkeyAuthentication even if it is already set up.
Merge pull request #15078 from gajdipajti/patch-1

Change how salt-ssh connects with sshpass.
Update documentation on salt-ssh

User must set NOPASSWD option for a non-root user to use sudo. 
Solves #12808.
Merge pull request #15141 from gajdipajti/patch-1

Update documentation on salt-ssh