migrate_to_reflex: convert pcconfig to rxconfig (#1270)

* migrate_to_reflex: convert pcconfig to rxconfig

fix #1269

* migrate_to_reflex: replace pynecone.io links with reflex.dev

reflex/utils/prerequisites.py

@@ -388,8 +388,10 @@ def migrate_to_reflex():
     updates = {
         "Pynecone": "Reflex",
         "pynecone as pc": "reflex as rx",
+        "pynecone.io": "reflex.dev",
         "pynecone": "reflex",
         "pc.": "rx.",
+        "pcconfig": "rxconfig",
     }
     for file_path in file_list:
         with FileInput(file_path, inplace=True) as file: