Change the tier badge of Geo to be PREMIUM

What does this MR do?

Change the tier badge of Geo to be PREMIUM and put it in the end of the sentence.

EE MR: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/7461

Author's checklist

• Apply the correct labels and milestone
• Crosslink the document from the higher-level index
• Crosslink the document from other subject-related docs
• Correctly apply the product badges and tiers
• Port the MR to EE (or backport from CE): always recommended, required when the ee-compat-check job fails

Review checklist

• Your team's review (required)
• PM's review (recommended, but not a blocker)
• Technical writer's review (required)
• Merge the EE-MR first, CE-MR afterwards