GitLab

* Added features.md and Getting Started guide.

* trimming newlines

* Adding hostfile discussion

* include/exclude emphasis

* Edits overview

* minor edits on the overview

* minor edits

* Fixing broken GPT2 links

* Clarify our relationship with Megatron-LM

* Update README.md

* Update README.md

* minor edits

* fix formatting
Co-authored-by: Shaden Smith <ShadenTSmith@gmail.com>
Co-authored-by: yuxionghe <yuxhe@microsoft.com>