README.md in numo-openblas-0.3.0 vs README.md in numo-openblas-0.3.1

- old
+ new

@@ -1,10 +1,10 @@
 # Numo::OpenBLAS
 
 [![Build Status](https://github.com/yoshoku/numo-openblas/workflows/build/badge.svg)](https://github.com/yoshoku/numo-openblas/actions?query=workflow%3Abuild)
 [![Gem Version](https://badge.fury.io/rb/numo-openblas.svg)](https://badge.fury.io/rb/numo-openblas)
-[![BSD 3-Clause License](https://img.shields.io/badge/License-BSD%203--Clause-orange.svg)](https://github.com/yoshoku/suika/blob/master/LICENSE.txt)
+[![BSD 3-Clause License](https://img.shields.io/badge/License-BSD%203--Clause-orange.svg)](https://github.com/yoshoku/suika/blob/main/LICENSE.txt)
 
 Numo::OpenBLAS downloads and builds [OpenBLAS](https://www.openblas.net/) during installation and
 uses that as a background library for [Numo::Linalg](https://github.com/ruby-numo/numo-linalg).
 
 ## Installation
@@ -60,14 +60,14 @@
 => 8
 ```
 
 ## Contributing
 
-Bug reports and pull requests are welcome on GitHub at https://github.com/yoshoku/numo-openblas. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [code of conduct](https://github.com/yoshoku/numo-openblas/blob/master/CODE_OF_CONDUCT.md).
+Bug reports and pull requests are welcome on GitHub at https://github.com/yoshoku/numo-openblas. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the [code of conduct](https://github.com/yoshoku/numo-openblas/blob/main/CODE_OF_CONDUCT.md).
 
 ## License
 
 The gem is available as open source under the terms of the [BSD-3-Clause License](https://opensource.org/licenses/BSD-3-Clause).
 
 ## Code of Conduct
 
-Everyone interacting in the Numo::Openblas project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/yoshoku/numo-openblas/blob/master/CODE_OF_CONDUCT.md).
+Everyone interacting in the Numo::Openblas project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the [code of conduct](https://github.com/yoshoku/numo-openblas/blob/main/CODE_OF_CONDUCT.md).