docs(plan): the plan records three releases, not one

0.5.0 carried the design, 0.5.1 the refusal of overlapping roots the design
states and 0.5.0 omitted, and 0.5.2 the separator defect the first
cross-platform run of the generator's fixture found.

Author: speak-agent

.agents/docs/2026-09-08-island-boundary-names-implementation-plan.md

@@ -173,7 +173,7 @@ descriptor holds exactly one `["latest"]` per platform table.
 **Files:** `examples/09-heterogeneous/boundary/**`,
 `examples/09-heterogeneous/cuda/app/**`, `examples/09-heterogeneous/sycl/app/**`.
 
-Each pins `plugins = { version = "0.5.0", ... }`, passes `roots` and a
+Each pins `plugins = { version = "0.5.2", ... }`, passes `roots` and a
 `layout_root`, and reaches the boundary through the qualified name. `boundary`
 additionally shows `strip_prefix`, because it is the example whose whole subject
 is the generated interface.
@@ -198,8 +198,11 @@ run locally before the pull request.
 
 ## T10 -- release
 
-Tag `v0.5.0`, GitHub release from the tag, `gtc` upload of the same bytes to
-GitCode, then T6.
+Tag the release, publish it from the tag, `gtc` upload of the same bytes to
+GitCode, then T6. This ran three times: 0.5.0 for the design, 0.5.1 for the
+refusal of overlapping roots that the design states and 0.5.0 omitted, and
+0.5.2 for the separator defect the first cross-platform run of the fixture
+found.
 
 ## T11 -- ecosystem verification