doc: move 8 collaborators to emeriti

As discussed in TSC email, I contacted 8 Collaborators whose last activity appears to be quite some time ago to suggest that they be moved to emeritus status until such a time as they will be active again. There were no objections from the 8 Collaborators or the TSC.

Checklist

• documentation is changed or added
• commit message follows commit guidelines

Affected core subsystem(s)

doc