docs: dire partout que la lecture par lot n'existe plus

Le contrat publie et l'api-contract etaient traites avec le retrait lui-meme ;
restaient les documents qui decrivaient readUnion comme la primitive de
lecture du paquet, ou qui nommaient le module disparu.

Ce que les lecteurs apprennent maintenant : lire un document, c'est
docs.sparqlQuery ancre dessus, et lire plusieurs documents, c'est cet appel
une fois par document -- avec la decision sur une lecture qui echoue ecrite
au point d'appel. Deux consequences sont dites plutot que decouvertes : une
lecture refusee leve au lieu de rendre une liste vide, et les sujets sous le
prefixe reserve urn:ng-eventually: reviennent dans le resultat, a l'appelant
de les ignorer -- sans aucun gain de droits, les deux registres qu'un
document ordinaire porte etant l'adresse de sa boite et, pour un document
public, la cle que son magasin sert deja a qui la demande.

Les briefs dates ne sont pas touches : ils decrivent un etat de juillet, et
le reecrire falsifierait ce qui avait ete decide alors.

examples/notebook/README.md

@@ -8,7 +8,7 @@ It exists for two reasons, and the second is the one that matters.
 
 **It is what the applicative e2e suite drives** (`packages/polyfill/e2e/notebook.ts`, `bun run test:e2e:app`). The other suite talks to a bag of methods on `window.__sdk`, which proves the functions run but never that an application can be written with them — and that gap shipped a real defect once: a document's inbox was green in tests and unusable in practice, because the harness handed an address across an identity boundary through a variable, something no application can do. Here each identity is its own browser page, and the only values that cross between them are the ones that cross in life: a note's reference, copied off one screen, and an identifier typed into a field.
 
-It has already paid for itself: writing it surfaced that `UnionSubject` returned `string` where the values are always document references (so a consumer had to cast whatever it had just read before passing it back), and that the access gate normalized what a user typed but not what the URL carried.
+It has already paid for itself: writing it surfaced that the then-published `readUnion`'s property bags returned `string` where the values are always document references (so a consumer had to cast whatever it had just read before passing it back), and that the access gate normalized what a user typed but not what the URL carried.
 
 ## What it exercises