Updated handbook to reflect appropriate MM territories

Why is this change being made?

Handbook needed to reflect correct Mid market territories

The handbook was incorrect. Updating these minor territories will reflect correct data/lead flow moving forward

Does this MR meet the acceptance criteria?

Yes

Conformity

• Added description to this MR explaining the reasons for the proposed change, per [say-why-not-just-what][transparency] Incorrect information for sales territories. [transparency]: https://about.gitlab.com/handbook/values/#say-why-not-just-what