This replaces #13567

Closes JabRef/user-documentation#578
Related to JabRef/user-documentation#579

• Adds Wix Toolset to Windows requirements.
• Recommends Bash for Windows.

I recommend Git for Windows because (1) it is installed with Git Bash and (2) it is commonly used by Windows developers to have a linux-like environment. This generally eliminates the need for separate Windows build instructions. I realize this is kind of pushy so would be happy to remove it from this PR and/or create an issue.

Steps to test

n/a

Mandatory checks

• I own the copyright of the code submitted and I license it under the MIT license
• [/] Change in CHANGELOG.md described in a way that is understandable for the average user (if change is visible to the user)
• [/] Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• [/] Screenshots added in PR description (if change is visible to the user)
• Checked developer's documentation: Is the information available and up to date? If not, I outlined it in this pull request.
• Checked documentation: Is the information available and up to date? If not, I created an issue at https://github.com/JabRef/user-documentation/issues or, even better, I submitted a pull request to the documentation repository.