[0kaba0hub]

Documents yarilo#2356 and #2357 (chart 2.4.5-dev.31).

• protocols/jmap.md, Identities: the account's own identities (login, identity_aliases, mayDelete: false); Identity/set create (email one of the account's addresses, else forbiddenFrom; mayDelete: true; creation id usable as #i), update (all but email), destroy (created only, forbidden on the account's own); the invalidProperties refusals; a created identity whose address leaves userdb is not listed and cannot send; storage file. Capability table row and the push table (Identity/set moves Identity) no longer say read-only.
• reference/rfcs.md: new RFC 8621 §6 row; §7 row drops "identities are read-only".
• architecture/parity.md: JMAP row.

[0kaba0]

APPROVED at e01cd5d. The Identities section states the behaviour of #2356 as merged: own identities with fixed ids and mayDelete: false, create with email from the account's addresses and forbiddenFrom otherwise, update of everything but email on both kinds, destroy of created ones only, the invalidProperties set, the address-leaves-userdb rule, the storage file. Capability table, push table, RFC rows and the parity row no longer say read-only, and the push paragraph now gives the one case the recompute still covers. Build green.