Move games/minetest to games/minimal and update README.txt

games/minimal/mods/legacy/textures/cooked_rat.png

games/minimal/mods/legacy/textures/dungeon_master.png

games/minimal/mods/legacy/textures/fireball.png

games/minimal/mods/legacy/textures/firefly.png

games/minimal/mods/legacy/textures/oerkki1.png

games/minimal/mods/legacy/textures/oerkki1_damaged.png

games/minimal/mods/legacy/textures/rat.png

mods/minetest/mods_here.txt