This updates the VoxeLibre documentation by replacing "Minetest" with "Luanti" and updating links.
Done:
* Update "Minetest" in documentation and comments to "Luanti"
* Update links to forums, ContentDB and Luanti project web page
Reviewed-on: https://git.minetest.land/VoxeLibre/VoxeLibre/pulls/4706
Reviewed-by: the-real-herowl <the-real-herowl@noreply.git.minetest.land>
Co-authored-by: teknomunk <teknomunk@protonmail.com>
Co-committed-by: teknomunk <teknomunk@protonmail.com>
