Make it clear that AMIDST has moved

[jensz12]

I was very confused about where to download AMIDST! So maby make it more clear, that it has moved to here https://github.com/toolbox4minecraft/amidst

[stefandollase]

Thanks for the request. I agree with you. Sadly @skiphs seems to be inactive again.

@skiphs If you read this issue, please also have a look at #92. There, I summarized the tasks that should be done after the first new stable release, which is out since several weeks. Thanks.