Remove plugin libraries' jar files

I don't know if this was allowed at all... 😁
To compile the resource yourself, you still need to download all of
these.

libs/plugins/README.md

@@ -1,20 +0,0 @@
-# Plugins
-A list of plugins, which are either required, recommended or just compatible with ShopChest.
-
-## Vault
-Vault is required to run ShopChest.
-It adds the economy system, but you need to have a supported economy system installed.
-
-## LWC
-LWC is a protection plugin.
-It's not required, but it's recommended to protect shops from hoppers, etc.
-
-## Lockette
-Lockette is also a protection plugin.
-It does basically the same as LWC, just in another way.
-Do **not** install LWC **and** Lockette at the same time, as it may lead to errors.
-
-## ClearLag
-ClearLag is a plugin, which is not required.
-With it you can remove all entities manually or in a specific interval.
-I added it here to the list, because ShopChest supports it. That means, the shop items won't get removed with it. *(Actually they will, but they get reloaded afterwards).*