proposal describes repo-host notify registrations missing from the alpha API

proposal 0016 describes repo-host notification subscriptions that the current spaces alpha does not expose. low severity, documentation/API mismatch found by source inspection, no live PDS repro

the proposal says registerNotify can subscribe to an individual repo on its repo host, and the API table mentions a repo parameter:

• proposal, write notifications
• proposal, API table

on PR #5187 at cd9bedbe1739691f7925ebbc6a4b1239a55bf327, the lexicon takes only space and service, says to call the space host, and the handler requires that host to serve the authority:

• registerNotify lexicon
• registerNotify handler

is repo-host registration still planned, or should the proposal describe space-host-only registration for this alpha? a client following the current proposal cannot express the repo-specific subscription against this API