docs(deployment): name the app as where @objectstack/organizations must be installed (cloud#1013)

The D5 boot-guard remediation list said "install @objectstack/organizations",
which was un-actionable while the CLI resolved the package against its own
realpath — installing it ANYWHERE did not lift the guard. Now that `serve`
resolves from the host app, the location is exact and load-bearing, so the
bullet says it: declare it in the served app's package.json. Same wording as
the fatal message the CLI prints, so the doc and the terminal agree.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019TYoxKa8yFLiDDh7tkBqtu

Author: claude

content/docs/deployment/tenancy-modes.mdx

@@ -112,7 +112,10 @@ The platform **refuses to boot** in this state:
 
 Resolve it one of three ways:
 
-- **install `@objectstack/organizations`** (the enterprise multi-org runtime); or
+- **add `@objectstack/organizations`** (the enterprise multi-org runtime) **to the
+  app you are serving** — declare it in that app's `package.json` and install it
+  there. The CLI resolves the package from the served app, not from the framework
+  it is linked out of, so installing it anywhere else does not lift the guard; or
 - **unset `OS_MULTI_ORG_ENABLED`** to run single-org; or
 - **set `OS_ALLOW_DEGRADED_TENANCY=1`** to boot anyway in an explicitly degraded
   single-org state.