nit: Update project guidelines to define approval policy

This patch documents the projects policy on PR approval, mainly that
PRs should have two different reviewers (excluding the PR owner)
approval rather than one reviewer adding both votes.

docs/source/development/01_guidelines.md

@@ -95,3 +95,11 @@ If at any time your patch no longer meets this criteria the label will be remove
 
 If you would like to bring attention to your patch before a reviewer has made it to your patch
 reach out in our [slack channel](https://redhat.enterprise.slack.com/archives/C03MD4LG22Z)
+
+## PR Approval Policy
+
+All pull requests must be approved by at least two reviewers, excluding the PR owner.
+
+Please note that this requirement is a project-specific guideline rather than a tooling constraint, as Prow does not currently support enforcing a minimum number of approvals.
+
+This policy is in place to ensure code quality and to minimize the risk of introducing breaking changes.