docs: describe project sharing as shipped on the settings page

The Groups card still called sharing "the upcoming sharing feature". It has
shipped — memory_visibility, groups, user_groups and project_shares are all
live — so the card now describes what group membership actually does:
read access for member groups, write access for read-write groups.

Authored on the fix/memory-list-project-filter branch on 2026-07-05 and never
committed; that branch is otherwise fully merged via PR #7.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

apps/web/app/(authed)/settings/page.tsx

@@ -63,7 +63,9 @@ export default async function SettingsPage() {
           </CardHeader>
           <CardBody className="text-sm text-fg-muted">
             OIDC group memberships from your IdP, refreshed at sign-in. Used
-            by the upcoming sharing feature to scope project visibility.
+            to scope project sharing &mdash; memories and snippets in a shared
+            project are readable by member groups and editable by read-write
+            groups.
           </CardBody>
         </Card>
       </div>