Adds content for init guide (new-repo CLI)
Adds content for the Getting Started -> Create a New Project in the new documentation site for 0.11.0.
Also, Next seems to generate files in docs/out/, which bloats the git history. So, docs/out/ was added to a .gitignore.
Test Plan: buildkite
Reviewers: sashank, yuhan
Reviewed By: yuhan
Differential Revision: https://dagster.phacility.com/D6670