Add templates and short guides for popular package managers

[eseiler]

Add some information on how to create packages in:

• brew (https://github.com/brewsci/homebrew-bio)
• conda (https://github.com/bioconda/bioconda-recipes)
• ...

It should include:

• A template (build.sh + meta.yml for bioconda; <package>.rb for brew)
• A small guide on how to create packages, i.e. creating a PR
• Some links with more information
• Caveats, e.g., you should not use -march=native for the packages