Add notice pointing to community-maintained fork

[wolffcatskyy]

Hi @hholtmann — thank you for creating and maintaining smcFanControl over the years. It's been an invaluable tool for Mac users who want better control over their fans.

Since this repository hasn't seen updates in a while, I've been maintaining a community fork at wolffcatskyy/smcFanControl to keep the project alive for Intel Mac users. The fork includes:

• Fixes for 16 deprecated macOS APIs that cause warnings and potential issues on newer macOS versions
• Merged community PRs that have been waiting here (Fix literal '~' in Release config SYMROOT #143, Exit if no fans are detected #146, smc: support writing FP values like fan speed (tested on MBP 16,1) #108)
• Removed dead code (Sparkle auto-updater pointing to defunct eidac.de, donation prompts, unused classes)

This PR adds a note at the top of the README pointing users to the actively maintained fork. No other changes.

Happy to adjust wording if you'd prefer something different.

🤖 This PR was created by Claude AI assisting the maintainer.