Document the "source" option in exclude-rules

[james-johnston-thumbtack]

Your feature request related to a problem? Please describe.

There is apparently a source option which is available under exclude-rules in order to exclude a rule from code lines that match a particular regular expression. After some amount of digging around and first considering filing an issue about exclusions at least for the lll linter, I found it mentioned here: #207 (comment)

Unfortunately this option is not documented on the False Positives page at https://golangci-lint.run/usage/false-positives/ which is where I would have expected it: searching the page for source yields zero results. This was actually one of the first places I looked to try to find out if such a feature might exist.

Instead, the only mention is at https://golangci-lint.run/usage/configuration/#issues-configuration in a passing example that doesn't go into the depth of explanation that the False Positives page does.

Describe the solution you'd like.

Add documentation for the source option to the False Positives documentation page.

Describe alternatives you've considered.

none

Additional context.

No response