You should probably ignore everything you see here on GitHub. The writing and engagement here is not meant for the wider audience of Holacracy users, and may be seriously confusing if you're not already a skilled Holacracy practitioner. Instead, try the Holacracy Community of Practice: http://community.holacracy.org.
No. This platform is to support Holacracy developers working on the next version of the Holacracy operating system, and the version you see here is the latest "under development" version - if this were software, it wouldn't even be released as an "alpha" or "beta" release yet, let alone a new version. You can find the official released version at http://holacracy.org/constitution.
I see you changed a rule in the Constitution here in GitHub; should my company start relying on the new rule?
No. the version you see here is the latest "under development" version (see prior question). You should only rely on rules in the version of the Constitution that your organization officially adopted.
I know Holacracy well, but I’m not very tech savvy. How do I use GitHub to contribute to evolving Holacracy?
You can start by orienting yourself with these basic resources about Version (Revision) Control in Open Source development and GitHub basics.