Contributors RTD page - add link to 'how to add"

[christinerogers]

Describe your problem in detail.

Tho this is pretty chicken-and-egg -- the RTD Contributors page should show a link "How to suggest/add a missing contributor name" -- because it's the most public version of the page.
cc @Remi-Gau thoughts on the easiest way to do this?

Describe what you expected.

No response

[Remi-Gau]

I think this relates to our contrib workflow PR: https://github.com/bids-standard/bids-specification/pulls