Document meaning of labels

Author: jieyouxu

README.md

@@ -51,6 +51,7 @@ from all the supported services.
 * [TOML schema reference](docs/toml-schema.md)
 * [Team maintenance](https://forge.rust-lang.org/infra/team-maintenance.html).
     * In particular, refer to [*Rules for changes to team repo*](https://forge.rust-lang.org/infra/team-maintenance.html#rules-for-changes-to-team-repo).
+* [Labels applied to issues and PRs](docs/labels.md)
 
 ## Using the CLI tool
 

docs/labels.md

@@ -0,0 +1,33 @@
+# Labels used in the `team` repository
+
+Some labels are setup to make it easier to figure out the status of an issue or PR, and allows
+contributors to filter issues/PRs by labels.
+
+## Labels are currently manually applied
+
+[`triagebot`][triagebot] is not currently set up for the `team` repository, as it would need write
+access (which needs to be tightly controlled). Thus, labels are currently manually applied and
+adjusted. See [threat model](./threat-model.md).
+
+## Meaning of labels
+
+- `needs-{team-repo,infra}-admin-review`: needs one of the [`infra-admins` or `team-repo-admins` or
+  one from both to review (and approve/reject)][team-repo-rules].
+- `needs-team-lead-review`: needs a relevant team or Working Group (WG) or Project Group (PG) lead
+  to approve.
+- Statuses:
+    - `S-waiting-on-{author,review,team}`: self-evident
+    - `S-has-concerns`: outstanding concerns that must be addressed
+    - `S-blocked`: blocked on *something*
+- Team labels: only `T-{infra,leadership-council}`, the latter is intended to help council members
+  to see what `team` PRs would need Council feedback or concerns the Council somehow.
+- `E-{easy,medium,hard}` and `E-help-wanted`: call-for-participation labels copied from
+  `rust-lang/rust`.
+- `needs-triage`: someone should try to figure out what the issue/PR needs/is/affects/is blocked on.
+- `needs-council-fcp`: something that requires the Council to FCP (outside `team` repo as rfcbot
+  isn't enabled).
+
+
+[triagebot]: https://forge.rust-lang.org/triagebot/index.html
+[team-repo-rules]:
+    https://forge.rust-lang.org/infra/team-maintenance.html#rules-for-changes-to-team-repo