Remove unnecessary warning and add other minor improvements

What does this MR do?

Fixes issues in Geo docs where one section of the documentation describes a feature as mandatory and another section says that the feature is not ready for production use.

Made other minor fixes while here.

Related issues

Problem found during review of: https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/7878.

Author's checklist

• Apply the correct labels and milestone
• 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