README: script/install stops when its target is this repo

Started from this repo with a path, the script writes into that clone,
so "stops when run here" was false.

Model: opus-5-5

README.md

@@ -143,7 +143,8 @@ alpine. We provide:
   extension); `make hooks` shims to it
 - `script/install` — fetch the vendored policy files from this repo over HTTP
   and write them into a repo (our own extension). It writes into the repo given
-  as its argument, or its own repo with no argument. It stops when run here.
+  as its argument, or its own repo with no argument. It stops when its target is
+  this repo.
 - `script/update-policy` — fetch the current `script/install`, run it on its own
   repo and commit the result without pushing (our own extension). It is for the
   repos that vendor the policy files. It stops when run here.