update README

Author: vuillaut

README.md

@@ -5,3 +5,22 @@ Generate a changelog listing all merged requests since the last release of the r
 ## Do it online: 
 [![Heroku](https://pyheroku-badge.herokuapp.com/?app=gitlab-release-notes)](https://gitlab-release-notes.herokuapp.com/)
 [![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/vuillaut/GitlabReleaseNotesGenerator/HEAD?labpath=generate.ipynb)
+
+
+## Install and run locally
+
+To install: 
+```
+pip install gitlab_release_notes
+```
+
+Then run:
+```
+gitlab-release-notes --help
+```
+
+## Heroku 
+
+Heroku is setup in the `heroku` branch.
+- make a new release of `gitlab_release_notes`
+- manually deploy from https://dashboard.heroku.com/apps/gitlab-release-notes/deploy/github choosing the heroku branch