Contributing Guidelines for newcomers

[zaleslaw]

We released the Contributing Guidelines for newcomers.

[zaleslaw]

Please, @avan1235 @mkaze @therealansh @devcrocod @d-lowl @dosier @kokorins spend some minutes and read.
There is a common practice for kotlinx projects and based on kotlinx.serialization guidelines with the addition of our informal practice.

Hope it will be helpful for you and new contributors.

[d-lowl]

Looks pretty good. Potential suggestion. Since it says (or used to say?) on a few issues for layer implementation "if possible, create a small trainable network with it (in your own GitHub) and attach a link here in the comments", it might be good to have a boilerplate repo, so devs can fork and use it for those examples.

[zaleslaw]

Great idea to have a skeleton/template repo, thanks for the addition