Develop content on pronoun use

this issue may belong in an alternative location, but I'm opening it so we don't lose it while we decide where it goes.

> In the prior update, one aim was to reduce the number of links to outside resources, to
> ward against link rot and improve control over maintenance. I'm ok with adding these
> for now, but we should consider building our own resources in this area.

"this area" is pronoun use

_Originally posted by @karenword in https://github.com/carpentries/instructor-training/issues/1411#issuecomment-1222940336_

Start by reviewing issue 1411 and the referenced comment, then determine where pronoun-use material belongs and what resource is needed. Done means the location and scope are agreed and the content is added there; this issue names no files or tests.

Written by the indexing model from the issue text.