BrigadierOpts is a successor to MCOpts, but varies widely in scope and usage. Brigadier did make producing and using commands much easier, but the implementations of it can be kind of clunky and rather rigid, so this mod is meant to alleviate that by making highly customizable but easy to use ways to interact with Brigadier.
Please refer to the Wiki for how to use the mod as a developer.
You are free to include the library using the steps above, which will automatically add all required files (license, notices) to your jar. If you modify it, you also have to include a changes file to outline roughly what you did.