Dashboard Link to local file

I have used this dashboard function successfully to create different views for my system however I'm trying to add a new link labelled "Documentation" for the side bar which would access a local HTML file I created that contains pertinent documentation (using iframe, but that isn't mandatory).

I cannot seem to make this work. I tried "file:///home/pi/documentation/guide.htm"
Any suggestions?

Why not try the forum / google search?

Many results... eg: https://discourse.nodered.org/t/display-pdf-file-on-dashboard/9803

Much appreciated.

Actually, I’m still a little unsure here. The very same browser that I’m running Dashboard with can (on an alternate tab) access the local file using file:/// no problem but on the Dashboard tab in the same session Dashboard can’t (or won’t).

When you enter or paste in the address bar, it is not a link.
As a href link it is only possible when you override the browser security settings.

See this info (yes this is another project, but it explains the issue)