Awesome
Custom Asset Meta data
A package which adds the ability to add metadata to assets(*) in Unity
(*) currently only Material is supported
Install
In the unity package manager in the top right corner, press the + and select "Add package from git URL" and enter "https://github.com/LogicalError/CustomAssetMetadata.git" This will install the package
Here, you can go to the sample tab to import an example project that uses CustomAssetMetadata