rcmds.biome/biome sets the biome of the chunk the player is standing in to [biome]. If (radius) is specified,
it will set the biome of all chunks in that radius from the chunk the player is standing in to [biome].
Doing the command without arguments will display a list of valid biomes to use for [biome].
If the changes are not immediately apparent, /fixchunk can be used to resend the chunk.
/biome plains - Changes the biome the player is standing in to plains.
/biome plains 3 - Changes the biome the player is standing in and all chunks within a 3 chunk radius to
plains.