Update readme references to main

README.md

@@ -65,9 +65,9 @@ If you use pyrolite extensively for your research, citation of the software woul
 [![Formatted with Black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/python/black)
 [![Code Quality](https://api.codacy.com/project/badge/Grade/fd9912a3faae43bf84a47e3da685d84c)](https://app.codacy.com/gh/morganjwilliams/pyrolite/dashboard?utm_source=github.com&utm_medium=referral&utm_content=morganjwilliams/pyrolite&utm_campaign=Badge_Grade)
 
-|                                                                                  **master**                                                                                  |                                                                                  **develop**                                                                                   |
+|                                                                                  **main**                                                                                  |                                                                                  **develop**                                                                                   |
 |:----------------------------------------------------------------------------------------------------------------------------------------------------------------------------:|:------------------------------------------------------------------------------------------------------------------------------------------------------------------------------:|
-|                               [![Unit Tests on Master](https://github.com/morganjwilliams/pyrolite/workflows/Unittest/badge.svg?branch=main)](https://github.com/morganjwilliams/pyrolite/actions?query=workflow:Unittest+branch:main)                                |                               [![Unit Tests on Develop](https://github.com/morganjwilliams/pyrolite/workflows/Unittest/badge.svg?branch=develop)](https://github.com/morganjwilliams/pyrolite/actions?query=workflow:Unittest+branch:develop)                                |
+|                               [![Unit Tests on main](https://github.com/morganjwilliams/pyrolite/workflows/Unittest/badge.svg?branch=main)](https://github.com/morganjwilliams/pyrolite/actions?query=workflow:Unittest+branch:main)                                |                               [![Unit Tests on Develop](https://github.com/morganjwilliams/pyrolite/workflows/Unittest/badge.svg?branch=develop)](https://github.com/morganjwilliams/pyrolite/actions?query=workflow:Unittest+branch:develop)                                |
 | [![Coverage Status](https://coveralls.io/repos/github/morganjwilliams/pyrolite/badge.svg?branch=main)](https://coveralls.io/github/morganjwilliams/pyrolite?branch=main) | [![Coverage Status](https://coveralls.io/repos/github/morganjwilliams/pyrolite/badge.svg?branch=develop)](https://coveralls.io/github/morganjwilliams/pyrolite?branch=develop) |
 
 **Maintainer**: Morgan Williams (morgan.williams _at_ csiro.au)