docs: JWT auth + anchors

advanced/user-auth/jwt.mdx

@@ -30,3 +30,7 @@ I want to set up authentication for my docs hosted at `docs.foo.com`. I want my
 To set up authentication with Mintlify, I go to my Mintlify dashboard and generate a JWT secret. I create a web URL `https://foo.com/docs-login` that initiates a login flow for my users. At the end of this login flow, once I have verified the identity of the user, I create a JWT containing the user’s custom data according to Mintlify’s specification. I sign this JWT with my Mintlify secret, create a redirect URL of the form `https://docs.foo.com#{SIGNED_JWT}`, and redirect the user.
 
 I then go to the Mintlify dashboard settings and enter `https://foo.com/docs-login` for the Login URL field.
+
+## Preserving Anchors
+
+Post-login, if you'd like to redirect to a specific anchor on the page, you can use the following format to create the redirect URL: `https://docs.foo.com/page#jwt={SIGNED_JWT}&anchor={anchor}`.