Add maintainer handle placeholder

Why is this change being made?

Trying to make this template more clear so that someone knows to mention the maintainer. I missed that this had to be replaced for months.

Does this MR meet the acceptance criteria?

Assign to DRI

• Did you assign this change to the correct DRI of the page or information you are changing?

Conformity

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