add a mcmahon as rd in apac

Why is this change being made?

• Added a new team member to the list of Regional Directors for APAC
• Update the EMEA RD to placeholder

these changes are to update the existing team and to make it easier for others to understand who is DRI in a region & who to talk to when needing help.

Does this MR meet the acceptance criteria?

Conformity

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what