Update README.rst

[rowanc1]

Typo Equality --> Equally.

[welcome]

💖 Thanks for opening your first pull request! 💖

Please make sure you read the following:

• Authorship Guidelines: Our rules for giving you credit for your contributions, including authorship on publications and Zenodo archives.
• Contributing Guide: What the review process is like and our infrastructure for testing and documentation.
• Code of Conduct: How we expect people to interact in our projects.

A few things to keep in mind:

• Remember to run make format to make sure your code follows our style guide.
• If you need help writing tests, take a look at the existing ones for inspiration. If you don't know where to start, let us know and we'll walk you through it.
• All new features should be documented. It helps to write the docstrings for your functions/classes before writing the code. This will help you think about your code design and results in better code.
• No matter what, we are really grateful that you put in the effort to do this! ⭐