[tests/selinux] pr775-checkpolicy-revdeps: adding gating guideline to README

[jan janasek <jjanasek@redhat.com>]

            A new commit has been pushed.

            Repo   : tests/selinux
            Branch : pr775-checkpolicy-revdeps
            Commit : 160b772afeed49fc961a0a81c07597698ffea2d7
            Author : jan janasek <jjanasek@redhat.com>
            Date   : 2025-08-26T13:03:09+00:00
            Stats  : +10/-0 in 1 file(s)
            URL    : https://src.fedoraproject.org/tests/selinux/c/160b772afeed49fc961a0a81c07597698ffea2d7?branch=pr775-checkpolicy-revdeps

            Log:
            adding gating guideline to README

Adds documentation to the README file to explain the test tiering system and its role in our gating process.
This clarifies the meaning of 'tier: 1/2/3' metadata and explains that older tags (e.g., tag:Tier1) have been deprecated.

Signed-off-by: Jan Janasek <jjanasek@redhat.com>

---
diff --git a/README.md b/README.md
index cd129dc..31b5c7d 100644
--- a/README.md
+++ b/README.md
@@ -3,6 +3,16 @@
 This repository contains set of test for SELinux kernel, userspace and policy.
 Tests are written using [beakerlib](https://github.com/beakerlib/beakerlib) with [TMT Metadata Specification](https://tmt.readthedocs.io/en/latest/spec.html).
 
+
+## Gating Guidelines
+Test tiers define a test's priority for our **gating process**.
+
+* **`tier: 1`**: Critical tests that must pass for any code merge. 
+* **`tier: 2`**: Important but non-critical tests.
+* **`tier: 3`**: Non-critical tests.
+
+All other tier metadata (e.g., `tag:Tier1`) is now deprecated.
+
 ## Plans
 
     $ tmt plans