store: a write inside a list checked where the rules judge it

Review 2, N9: the API checked a write's capability on the path asked
(servers/list/3/name), the rules on the list it is in (servers/list):
a user whose capability lay inside a list had every such write pass the
API and refused by the node's own judgement (403, after rolling the
document back).

inspect::placed places a write's path in the document by the rule the
inspector places operations by (Place::child: cut after the first list
or text on the way), and the store's writes check capabilities there.
One rule for both; a test checks placed against the paths the inspector
finds in the change such a write makes.

1 files changed, 3 insertions, 1 deletions

diff --git a/docs/access.md b/docs/access.md
index d1f69e1..b853b5a 100644
--- a/docs/access.md
+++ b/docs/access.md
@@ -59,7 +59,9 @@ Every request is checked against the registry, as the node serving it holds it:
 change to it counts on a node as soon as it has reached it.
 
 * **The store** (`/store`, `/stream`): writing a path (`PUT`, `POST`, `DELETE`) takes
-  `write` on it; `?prune=true` deletes maps left empty only up to the highest one the
+  `write` on it, or, inside a list or text, on the list, as every node judges the
+  change (a list's items have no paths of their own, Changes judged on every node,
+  below); `?prune=true` deletes maps left empty only up to the highest one the
   user may write. Reading takes `read`: of a place the user may read only partly, it
   sees the keys on the way to what it may read, as a directory one may pass through
   but not list (a capability on `servers/eu` shows `servers` with `eu` alone in it),