clean up in the pkg state.
Added date to release notes for recent salt versions

These dates were pulled out of the Git commit for the tag (with a Vim
macro). I didn't go back before we started tagging releases with
annotated tags since that would take some mailing list archaeology. Also
there might be a couple instances where the tag came plus or minus a day
or two from the announcement.

Closes #9426
Updated the master troubleshooting docs with an example of modifying the limits.conf.
Merge pull request #9428 from gravyboat/develop

Update to pkg state example, and master troubleshooting topic.
Added a line explaining that the user would need to re-establish their sessions as the user they modified the limits for in the master troubleshooting guide.
Merge pull request #9429 from gravyboat/develop

Master troubleshooting guide update regarding ulimit refresh.
Merge pull request #9430 from terminalmage/docs

Add new XMPP module/state to docs
Fix docs for the "Understanding State Ordering" tutorial

"code-block" directives require a blank line before them.
related to #9274, another place needs exception handling
updated suse spec to 0.17.4
Merge pull request #9431 from malept/fix-states-ordering-docs

Fix docs for the "Understanding State Ordering" tutorial
Merge pull request #9432 from Cofyc/fix_exception_handling_in_ps

related to #9274, another place needs exception handling
Merge pull request #9433 from aboe76/develop

updated suse spec to 0.17.4
Adding execution module and state for @PagerDuty
Merge pull request #9434 from techhat/pagerduty

Adding execution module and state for @PagerDuty
Add new pagerduty module/state to docs