Doc: Update Versioned Plugin Reference to use short titles for SNMP 4.0.0

[karenzone]

The SNMP integration plugin at 4.0.0 uses complete titles in left name.
Implement plugin headers to correct.

Backstory

Hooking up an integration plugin is an iterative process. We can't implement headers until all files are in place. If we try, we get broken links and failed docs builds.

Now that the SNMP integration is completely in place, we can fix the short titles for v4.0.0.