add readme

README.md

+# The Dynare Website
+
+## Pre-requisites
+
+- [Ruby](https://www.ruby-lang.org/en/)
+- [Jekyll](https://jekyllrb.com/)
+
+## Instructions
+
+- clone this repository: `git clone git@git.dynare.org:Dynare/website.git`
+- `cd website`
+- `bundle install`
+- `bundle exec jekyll serve`
+
+## To push version to server
+
+- `JEKYLL_ENV=production bundle exec jekyll serve`
+- push the contents of `_site` folder to server