On this page, the type of tags is listed as string. While it does accept a single string as a value, it also accepts an array of strings (as you’d expect from the plural name). This is particularly confusing since the example only shows the single-string case.
I’d be happy to take a stab at fixing this if someone could point me in the right direction. I would have guessed that these docs were auto-built from here; but the bug presumably lies in the parsing code rather than the parsed code, especially since the linked snippet defines tags as a StringSlice.
If this is working-as-designed (maybe string is always considered an alias for string or string[]?), another Example showing the multi-tag use-case would be great!