Update repo settings (#1846)

Author: trask

.github/repository-settings.md

@@ -2,5 +2,28 @@
 
 Same
 as [opentelemetry-java-instrumentation repository settings](https://github.com/open-telemetry/opentelemetry-java-instrumentation/blob/main/.github/repository-settings.md#repository-settings),
-except that the rules for `gh-pages` and `cloudfoundry` branches are not relevant in this
-repository.
+except for
+
+- The rules for `gh-pages` and `cloudfoundry` branches are not relevant in this repository.
+
+and the enablement of merge queues below.
+
+## Merge queue
+
+Needs to be enabled using classic branch protection (instead of rule set)
+because of our use of the classic branch protection "Restrict who can push to matching branches"
+which otherwise will block the merge queue from merging to main.
+
+### Restrict branch creation
+
+- Additional exclusion for `gh-readonly-queue/main/pr-*`
+
+### Classic branch protection for `main`
+
+- Require merge queue: CHECKED
+  - Build concurrency: 5
+  - Maximum pull requests to build: 5
+  - Minimum pull requests to merge: 1, or after 5 minutes
+  - Maximum pull requests to merge: 5
+  - Only merge non-failing pull requests: CHECKED
+  - Status check timeout: 60 minutes