Mention how to find the root folder

[za3k]

Preview: https://github.com/za3k/multimc-wiki/blob/master/Directory-Structure.md

[za3k]

@Zetabite Github has a feature where I believe you should be able to make changes to my PR yourself because I've given you permissions. For next time around.

The other small point I'll mention is that the docs say "Directory" consistently, but MultiMC itself says "Folder". I assume people know they're the same?

[Zetabite]

The other small point I'll mention is that the docs say "Directory" consistently, but MultiMC itself says "Folder". I assume people know they're the same?

Always in for consistency

[za3k]

Always in for consistency

Sorry I'm not sure what this means.

[Zetabite]

You are welcome to make it more consistent

[za3k]

Done. Especially note that I changed the filename, in case any links need updated. Feel free to change the filename back yourself if you don't want to break things.