add readme

README.md

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+# `ir_metadata`
+
+[![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/irgroup/ir_metadata/blob/master/resources/demo.ipynb)
+[![DOI](https://zenodo.org/badge/DOI/10.5281/zenodo.5997491.svg)](https://doi.org/10.5281/zenodo.5997491)
+
+## About
+
+This repository hosts the underlying resources of the `ir_metadata` website.
+
+`ir_metadata` is an extensible metadata schema for information retrieval experiments.
+
+Please visit the [website](https://irgroup.github.io/ir_metadata/) for more information.
+
+## How to edit and contribute to the website
+
+The website is built with [MkDocs](https://www.mkdocs.org/) and the corresponding [Material theme](https://squidfunk.github.io/mkdocs-material/). 
+
+First, install both packages.
+```
+pip install mkdocs mkdocs-material
+```
+
+Having edited the contents, preview the changes locally.
+```
+mkdocs serve -a localhost:8000
+```
+
+Having committed your changes to this repository, update the rendered website with the following commands.
+```
+mkdocs gh-deploy
+```