README.md in circleci-bundle-update-pr-4.0.7 vs README.md in circleci-bundle-update-pr-4.0.8

@@ -1,13 +1,13 @@
 # Circleci::Bundle::Update::Pr
 
-[![Build Status](https://img.shields.io/circleci/project/github/masutaka/circleci-bundle-update-pr/master.svg?logo=circieci&style=flat-square)][circleci]
+[![Build Status](https://img.shields.io/circleci/project/github/masutaka/circleci-bundle-update-pr/main.svg?logo=circieci&style=flat-square)][circleci]
 [![License](https://img.shields.io/github/license/masutaka/circleci-bundle-update-pr.svg?style=flat-square)][license]
 [![Gem](https://img.shields.io/gem/v/circleci-bundle-update-pr.svg?logo=ruby&style=flat-square)][gem-link]
 
 [circleci]: https://circleci.com/gh/masutaka/circleci-bundle-update-pr
-[license]: https://github.com/masutaka/circleci-bundle-update-pr/blob/master/LICENSE.txt
+[license]: https://github.com/masutaka/circleci-bundle-update-pr/blob/main/LICENSE.txt
 [gem-link]: http://badge.fury.io/rb/circleci-bundle-update-pr
 
 `circleci-bundle-update-pr` is an automation script for continuous bundle update and for sending a pull request using [`Scheduling a Workflow of CircleCI`](https://circleci.com/docs/2.0/workflows/#scheduling-a-workflow).
 
 By requesting a nightly build to CircleCI with an environment variable configured in `circle.yml` or `.circleci/config.yml` to execute this script, bundle update is invoked, then commit changes and send a pull request to GitHub repository if there some changes exist.
@@ -82,11 +82,11 @@
     triggers:
       - schedule:
           cron: "00 10 * * 5"
           filters:
             branches:
-              only: master
+              only: main
     jobs:
       - continuous_bundle_update
 ```
 
 NOTE: Please make sure you replace `<username>` and `<email>` with yours.
@@ -102,10 +102,10 @@
 ```
 
 By default, it works only on master or main branches, but you can also explicitly specify any branches rather than only these branches by adding them to the arguments.
 
 ```
-$ circleci-bundle-update-pr <git username> <git email address> master develop topic
+$ circleci-bundle-update-pr <git username> <git email address> main develop topic
 ```
 
 You can also add the following options:
 
 ```