Create post-interview instructions page
See #3322 (closed) for context
This merge request moves the instructions for post-interview processes to a standalone page, currently titled "offers-and-contracts", although I considered just "post-interview."
These sections currently take up a serious chunk of space on the interviewing page, and they only apply directly to a certain subset of the readers on that page (i.e. the hiring team).
@BarbieGitLab @kpursel what do you think?
Note: because I don't want to confuse anyone who might be referring to the existing page for that information, I've written a tiny bit of text re-directing them to the new page for post-interview processes