enter pre-release mode for Start, add main to release triggers

Author: atilafassina

.changeset/pre.json

@@ -0,0 +1,8 @@
+{
+  "mode": "exit",
+  "tag": "alpha",
+  "initialVersions": {
+    "@solidjs/start": "2.0.0"
+  },
+  "changesets": []
+}

.github/workflows/release.yml

@@ -4,6 +4,7 @@ on:
   push:
     branches:
       - 1.x
+      - main
 
 concurrency: ${{ github.workflow }}-${{ github.ref }}