Remove operator ref

Create LICENSE

Merge pull request #3 from airflow-plugins/mailgun-plugin

Update README.md

link authentication page

reorg and remove astronomer language

Merge pull request #2 from airflow-plugins/gcp_ex

Added getting started with GCP example

Add Mailgun Plugin

Adjust formatting

typo

Merge branch 'master' of https://github.com/airflow-plugins/Getting-Started

add contribution guidelines

add operator section

update tutorials