About this folder:

This folder is used by MCEdit and pymclevel to store different versions of the
Minecraft Server to use for terrain generation. It should have one or more
subfolders, one for each version of the server. Each subfolder must hold at
least one file named minecraft_server.jar, and the subfolder's name should
have the server's version plus the names of any installed mods.

There may already be a subfolder here (for example, "Release 1.7.10") if you have
used the Chunk Create feature in MCEdit to create chunks using the server.

Version numbers can be automatically detected. If you place one or more
minecraft_server.jar files in this folder, they will be placed automatically
into well-named subfolders the next time you run MCEdit. If a file's name
begins with "minecraft_server" and ends with ".jar", it will be detected in
this way.