I may be missing something fundamental here.
If I go to the Ignition 8.1 online documentation and type something into the search box, it returns results for every version of Ignition (EG here I typed "pending" into the search box):
Is there anyway to limit the search results only to version 8.1? I took a look at the "search tips", the "filter results by", and the "advanced search", but nothing leaps out as how to restrict the results to only version 8.1.
There are two search boxes, one on the top left and one on the top right. I believe the one on the left only searches the current selected version, where the top right one will search in all versions.
No wonder I was confused. Two boxes labeled "Search" with totally different behaviors!
I didn't know the difference until I saw your question and checked 
Myriad issues (such as this) with Confluence have the docs team actively migrating to an alternate platform for the manual.