Add shards executable to shims path

[epergo]

Right now when you install crystal using asdf you can't access shards command just because it only adds executables in your_installed_crystal_version/bin and shards command is placed in your_installed_crystal_version/embedded/bin

Just as ASDF documentation for creating plugins says (https://github.com/asdf-vm/asdf/blob/master/docs/creating-plugins.md) I have added a new file bin/list-bin-paths where I specify both bin and embedded/bin as directories that hold executables to be linked when running asdf reshim crystal

[mgxm]

Thank You! 👍