Add in point to potentially invite an additional designer as (soft) reviewer

Regarding our latest conversation in the UX weekly agenda: Adding in a specific point to potentially (not mandatory, so more of a suggestion) ask for a second set of designer eyes on your work/process inside of an issue.

Feedback welcome, otherwise let's get this merged!

/cc @cperessini @dimitrieh @hazelyang @jkarthik @pedroms @sarrahvesselov @sarahod @tauriedavis @katokpara @matejlatin @andyvolpe