Improve `make help` output formatting

Current output uses the formatting of `* description of the command: make command` aka `value - key`, it is a somewhat unusual way to format command reference lists, IMO. As I actively use make commands from SP currently, and sometimes need to them up, I constantly stumble upon this. Swapping to `key - value` order would make it a bit more conventional.

Also, it might be worth considering documenting the commands next to the code and just [grep and printf the commands with their descriptions](https://marmelab.com/blog/2016/02/29/auto-documented-makefile.html). I don't believe the Makefile changes often though, so it might be just a nice-to-have.