docs: tighten spec wording

docs/specs/GRM-173.md

@@ -23,16 +23,15 @@ remove an object whose `lease-until` is in the future; expired leases are
 reclaimable. Existing `GITEA-ACTIONS-TASK` name-prefix and `status=exited`
 guards are retained for unlabeled objects.
 
-REQ-2: Introduce a single shared cleanup script
-(`runner-cleanup.sh`, templated next to the healthcheck script) invoked with
-`--tier routine|pressure|critical`. It replaces all inline prune logic in
-`docker-prune.service` and the healthcheck. Every prune is scoped: volumes and
-networks get `label!=`/`until=` filters at every tier (no unfiltered volume or
-network prune remains); images matching `gitea_runner_keep_images` are never
-removed, so warm base layers survive critical pressure.
+REQ-2: Introduce a single shared cleanup script (`runner-cleanup.sh`,
+templated next to the healthcheck script) invoked with
+`--tier routine|pressure|critical`, replacing all inline prune logic in
+`docker-prune.service` and the healthcheck. Every prune is scoped (leases,
+`until=` where supported); images matching `gitea_runner_keep_images` are
+never removed, so warm base layers survive critical pressure.
 
-REQ-3: Watermark-tiered behavior. `routine` (timer) prunes aged resources only.
-`pressure` (disk >= warn) prunes unowned resources older than 1h. `critical`
+REQ-3: Watermark-tiered behavior: `routine` (timer) prunes aged resources;
+`pressure` (disk >= warn) prunes unowned resources older than 1h; `critical`
 (disk >= critical) drops age limits but still honors leases, keep-images, and
 never removes running or `GITEA-ACTIONS-TASK` containers.