Provide guidelines for the Metrics Team's Java projects

This is the parent issue for defining

contributor's guidelines
coding style guidelines
release process description
(more?)

for java projects.

This issue serves for discussing "meta" questions like finding a central location and defining the structure.

The central place could be another git repository metrics-team-meta (or some better title), which could hold all documents like coding style guides for the various languages used by the Metrics-Team, guides and documents covering more than one Metrics-Team project, and other docs like the road-map.)

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information