New HB page describing Support's change management process

Why is this change being made?

The Support Leadership Team has no agreed-upon processes for introducing and managing change. We're very inefficient at it and we are putting at risk our ability to deliver support to GitLab's customers in a consistent way worldwide.

This new page summarizes the challenges we face in this area and will be the SSOT for our change management process.

How will this merge request impact page speed?

This is a new page.

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