Switch from master to main to start v3

.github/workflows/ci.yml

@@ -9,7 +9,7 @@ on:
   push:
     # filtering branches here prevents duplicate builds from pull_request and push
     branches:
-      - master
+      - main
       - "v*"
     # always run CI for tags
     tags:

README.md

@@ -616,7 +616,7 @@ support using `{{link}}` & friends in render tests, you can use the
 
 [tests-application]: https://guides.emberjs.com/release/testing/testing-application/
 [tests-render]: https://guides.emberjs.com/release/testing/testing-components/
-[setup-link]: https://github.com/buschtoens/ember-link/blob/master/addon-test-support/setup-link.ts
+[setup-link]: https://github.com/buschtoens/ember-link/blob/main/addon-test-support/setup-link.ts
 
 ```ts
 import { click, render } from '@ember/test-helpers';