Add new Diamond Tier for sponsorship

[nzakas]

What problem do you want to solve?

Our top sponsorship tier is at $2,000, which may lead people to believe that's the maximum they can donate.

What do you think is the correct solution?

Add a new Diamond tier at $5,000.

Participation

• [x] I am willing to submit a pull request for this change.

Additional comments

No response