Add Maximum Price to Hardware Table - Related to: gitlab-org/gitlab-design#870

Why is this change being made?

The Spending Company Money page in the handbook does not provide adequate guidance on how much a new employee or current team member can spend on home office supplies.

About this change:

• Renamed "Average Price in USD" column to "Maximum Reimbursement in USD"
• Added the following guidance: "...any purchase that will cost GitLab more than the Maximum Reimbursement Price will require approval from your Manager and Accounting"

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