📝 Add Cursor support for Mac key-repeat settings

[thoth2357]

Add Cursor text editor to the Mac setup instructions for enabling key-repeat functionality. This allows Cursor users to properly configure key-repeat behavior when using VSCodeVim by running the appropriate defaults write command.

What this PR does / why we need it:

This PR adds support for the Cursor text editor in the Mac setup instructions. Cursor is gaining popularity as a VS Code fork with AI integration, and users need the same key-repeat configuration as VS Code for VSCodeVim to work properly.
Without this setting, Cursor users experience the default macOS press-and-hold behavior instead of key repetition, significantly impacting the Vim experience.

Which issue(s) this PR fixes
No existing issue, but this is a proactive documentation update to support Cursor users.

Special notes for your reviewer:

• This is a simple documentation change that follows the existing pattern for other VS Code variants (VS Code, VS Code Insiders, VS Codium)
• The command has been tested and confirmed working on Cursor
• The change maintains the consistent formatting of the existing documentation
• This helps reduce support requests from Cursor users who might otherwise need to ask about key-repeat configuration