We should see if this can be fixed in godoc instead. The text in the documentation seems valid. It's a sentence that ends with a period, and a URL happens to be at the end of that sentence. The sentence is inside round brackets.
I suspect the round brackets are making it not recognize the period at the end of a sentence.
If we can fix this in godoc, that means a lot of Go documentation doesn't have to change to avoid this pitfall. I suspect there's more code in the wild that has a similar pattern.
@dmitshur I misspoke about this being done elsewhere, I had noticed other places where we didn't include the trailing period when referencing an issue in a comment (such as src/cmd/go/internal/lockedfile/internal/filelock/filelock_fcntl.go:16) but didn't realize that they weren't being included in the documentation.