Update approval rule description to accurately reflect the requirements

Author: shenanigansd

.github/review-policy.yml

@@ -35,7 +35,7 @@ approval_rules:
  options:
  ignore_update_merges: true
 - name: staff or contributor
- description: Two members of the staff or contributors team must leave an approval
+ description: One member of the staff or contributors team must leave an approval
  requires:
  count: 1
  organizations: ["python-discord"]