Improve and actualize info on Luanti forks

[wmikita]

this is pretty much just a clean-up change for Voxelands and Freeminer.

1. add more info on Voxelands, including my abandoned fork in maintenance status;
2. mention that Blocklife is no longer maintained;
3. actualize maintenance status on Freeminer and add some info about its content.

[rollerozxa]

Changes look good, could you just add your username to the dictionary in cspell.json to make the CI pass

[wmikita]

Changes look good, could you just add your username to the dictionary in cspell.json to make the CI pass

done!

[wsor4035]

lgtm