Documentation on mmexternal parameter forcesingleinstance does not describe anything but points to non-existing topic

[selivan]

https://www.rsyslog.com/files/temp/doc-indent/configuration/modules/mmexternal.html :

forcesingleinstance

This is an expert parameter, just like the equivalent omprog parameter. See the message modification plugin’s documentation if it is needed.

The issue is:

• omprog does not seem to have any equivalent or related parameter.
• that topic already is message modification plugin’s documentation, referring itself.

A description of what and how this parameter does should be there instead.