docs: quote the loopback regex actually deployed on the provider

The pattern in the walkthrough was written from memory and differs from the
one on the `shared-memory-mcp` provider in a way that matters: `…:[0-9]+/.*`
requires a path component, so it fails to match a bare
`http://localhost:5693`, which the deployed `…:\d+(/.*)?$` accepts. Copy the
live value verbatim instead.

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

docs/oidc-entra-id.md

@@ -241,7 +241,7 @@ prompt. See README → *Which redirect URIs to register*.
 `http://localhost` redirect URIs, so the single registration
 `http://localhost/callback` matches `http://localhost:33418/callback`,
 `http://localhost:9999/callback`, and any other port. This is Entra's
-equivalent of the Authentik regex (`http://(localhost|127\.0\.0\.1):[0-9]+/.*`)
+equivalent of the Authentik regex (`^http://(127\.0\.0\.1|localhost):\d+(/.*)?$`)
 the README mentions — users can pick any `--callback-port` without
 re-registering.