Fixes #1364

Description

• Adds installation instructions to release release candidate
• Bump release candidate number, as combining release candidate labels and post-release labels is ill-advised by the python docs:

Creating post-releases of pre-releases is strongly discouraged, as it makes the version identifier difficult to parse for human readers. In general, it is substantially clearer to simply create a new pre-release by incrementing the numeric component.

See https://packaging.python.org/en/latest/specifications/version-specifiers/#pre-releases