Document regex support in include/exclude patterns

[VirtualTim]

This information is very useful, but also very hidden. It is not mentioned at all for include patterns, and only briefly mentioned for exclude patterns. This PR makes the information more discoverable.

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[VirtualTim]

I wasn't 100% sure on the wording, or if this was the right place to document this, but I thought that if regex and regular expression are mentioned in a few places, it should at least make it easier for users to find this documentation.
It's better than nothing.