Adds onnx model instructions

version 0.4.7

Updated environment.yml to remove builds

Merge pull request edbeeching#13 from r0nk/patch-1

Update INSTALLATION.md to fix out of order conda installation instruction.

Merge pull request edbeeching#12 from edbeeching/doc_updates

Doc, env and checkpoint updates for version 0.2

Added windows exports for the example games