Document: How to build the docs

docs/README.md

@@ -0,0 +1,24 @@
+# Greenlight docs
+
+The docs are hosted on https://blockstream.github.io/greenlight/
+
+## Contributing to the documentation
+
+You must have a working installation of `python` and `poetry` to contribute to the docs.
+
+To install dependencies make sure you are at the root of the repository
+
+```
+poetry install --with-only docs
+```
+
+To build the docs
+
+```
+cd docs; mkdocs build
+```
+
+To serve the docs locally
+```
+cd docs; mkdocs serve
+```