Update references for default branch rename (#119)

.circleci/config.yml

@@ -53,4 +53,4 @@ workflows:
             tags:
               only: /.*/
             branches:
-              only: master
+              only: main

README.md

@@ -73,7 +73,7 @@ firefox site/index.html
 ## Publish
 
 To publish your report, create a pull request and get review.
-Once your report is merged to master,
+Once your report is merged to main,
 it will automatically be pushed to [dev RTMO]
 
 For example, using [GitHub's CLI, `hub`](https://github.com/github/hub):