Donate: Update Corporate Sponsorship FAQ

[marcuspollio]

• Update corporate sponsorship FAQ

[marcuspollio]

@maxwxyz
FYI at some FPA meeting (don't remember which one exactly right now, I will have to look at the notes), it was agreed to not have a "Corporate" or higher tier sponsorship level for now (i.e. we only keep normal, bronze, silver, and gold).
Yorik will investigate and discuss whether higher tiers are wanted, and if yes, those will be added later.

I have a local branch to remove that tier and fix some issues with the donation form.
I will ping you for testing once I update this PR, OK?

[maxwxyz]

sure