[DOCUMENTATION] Utility Icons Seemingly Don't Allow for Colour Overides

[ThisIsMarkJones]

Please share the area or functionality of the Documentation need/issue

I am support an attendee at the Housing Commons Sprint to set up a demo of Indicators for the project their group is working on. In our work today we have noticed that Utility SLDS icons don't seemingly allow for colour overrides.

Below is a screenshot of the configuration for a missing email Indicator Item that I have configured:

As you will see in the screenshot I set the background colour to white (#FFFFFF) and the foreground to red (#FF0000). When displaying the indicator in the UI, the utility displays in grey, as shown in the screenshot below.

However, when I change the icon to the standard email icon from SLDS, the colour changes based on my configuration:

If appropriate, please articulate as best as possible where the documentation is insufficient or doesn't seem clear

Honestly, I think it just needs to be either a footnote someone noting something like "please be aware that SLDS Utility icons do not allow for color overrides". That should suffice I think, alternatively maybe it could become an answer for an FAQ.

If appropriate, please provide documentation or adjustments