Clarify native-installation-instructions.md about Ruby installation

[olleolleolle]

Description of the issue 📄

This is a wording improvement request.

native-installation-instructions.md mentions lots of literal version numbers such as "3.4.7" - but the tools involved read that file (.ruby-version)for a specific value.

Steps to fix 🛠

• Check that rvm and rbenv both can install directly using some version-implicit command (rvm install rather than rvm install 3.4.7).
• Clarify the text file

To do 📋

• [ ] Claim this issue (comment below, or assign yourself if you are part of the codebar org)
• [ ] Fork and clone the repository
• [ ] Update the relevant files. Follow the steps to fix section in this issue.
• [ ] Commit your changes as one commit. Use the title of this issue as your commit message
• [ ] Submit a pull request
• [ ] Mention this issue in the PR description by including it's number
• [ ] Have your pull request reviewed & merged by a codebar team member