Update message when users try to update from 1st to 2nd Gen function (#7611)

* Update message when users try to update from 1st to 2nd Gen function using the same function name.

CLI has always block the transition 1st Gen to 2nd Gen in the CLI - change here simply update the product name and point users to our public doc that documents changes necessary to transition to 2nd gen function.

Aside: Cloud Run functions doesn't allow for 1st and 2nd gen functions to share the same name.

* messaging nit.

* Say 'see' instead of 'please'.

---------

Co-authored-by: joehan <[email protected]>

Author: taeold

src/deploy/functions/release/planner.ts

@@ -316,9 +316,8 @@ export function checkForIllegalUpdate(want: backend.Endpoint, have: backend.Endp
 export function checkForV2Upgrade(want: backend.Endpoint, have: backend.Endpoint): void {
   if (want.platform === "gcfv2" && have.platform === "gcfv1") {
     throw new FirebaseError(
-      `[${getFunctionLabel(
-        have,
-      )}] Upgrading from GCFv1 to GCFv2 is not yet supported. Please delete your old function or wait for this feature to be ready.`,
+      `[${getFunctionLabel(have)}] Upgrading from 1st Gen to 2nd Gen is not yet supported. ` +
+        "See https://firebase.google.com/docs/functions/2nd-gen-upgrade before migrating to 2nd Gen.",
     );
   }
 }