Issue 320 and ADR 0253: a condition says itself to the operator in plain words

The operator could not read the mesh's notifications: they were the summary meant
for an agent, with ids, commits, keys and verbs, in UTC. The condition now carries
a headline, an explanation and a resolved line beside its summary.

00-META/glossary.md

@@ -421,6 +421,11 @@ asking, never the act. **Decided by** ADR 0152, 0175, 0234.
   holder of kind `desktop`) and not *bot* (that is one service's account).
 - **router** — the module that holds the `operator-channel` seat, orders the channels and checks every
   sender ([ADR 0234](../02-DECISIONS/0234-the-mesh-holds-a-conversation-with-its-operator.md)).
+- **headline / explanation / resolved line** — what a condition says to the operator in plain words: a
+  few words naming the thing and what is wrong; one or two sentences on what happened, what it means and
+  whether to act; the line said when it clears. Carried by the condition beside its **summary**, which
+  keeps the plans, commits and verbs for whoever looks closer
+  ([ADR 0253](../02-DECISIONS/0253-a-condition-says-itself-to-the-operator-in-plain-words-beside-its-summary.md)).
 - **ask** — a request for the operator's input, of a declared kind (yes-no, one-of, text, number,
   date, acknowledge). An **authorising ask** is one whose answer performs an action; the controller
   holds it and checks its proofs (ADR 0234).