Switch to using separate site for archive

README.md

@@ -4,7 +4,7 @@
 
 Flutter Gallery was a resource to help developers evaluate and use Flutter.
 It is now being used primarily for testing. For posterity,  the web version
-remains [hosted here](https://gallery-flutter-dev.web.app).
+remains [hosted here](https://flutter-gallery-archive.web.app).
 
 We recommend Flutter developers check out the following resources:
 

firebase.json

@@ -1,7 +1,7 @@
 {
   "hosting": [
     {
-      "target": "staging",
+      "site": "flutter-gallery-archive",
       "public": "build/web",
       "ignore": [
         "firebase.json",
@@ -10,7 +10,7 @@
       ]
     },
     {
-      "target": "prod",
+      "site": "gallery-flutter-dev",
       "public": "build/web",
       "redirects": [
         {