Hi! I’m interested in contributing a small library. I’ve read this page:
I’d like to know more about spark.json but the link to the specification is broken:
https://www.spark.io/spark_library_schema_v1.json
Is there an updated uber library example or link to this spec?
There isn’t really a lot to know about spark.json
If you navigate to any well formed library in Build, you can follow the GitHub link and just have a peek at their spark.json file.
Copy and adapt it to your needs.
That’s how I did it anyway 
e.g.
BTW, there will be a new - more Arduino compatible - library structur introduced soon, which will require library.properties and project.properties instead.
Update:
I see, you’ve already opened an issue on the uber-library repo 
The version string sets the version number in Particle Build, has to be three dot seperated numbers only (no 0.0.1a possible) and has to be greater than any already published version number to be valid.
The license string as not checked against any lookup table (yet) - it just needs to be present.
I guess it’s safe to apply the (fitting) Arduino rules here too.