Add Docker install instructions (#446)

* Add Docker install instructions to README

* Add docker instruction to docs

* Fix whitespace

Author: mfisher87

README.md

@@ -56,6 +56,15 @@ and to install into a particular conda environment with [`mamba`](https://mamba.
 mamba install --channel conda-forge jupytergis
 ```
 
+#### With Docker
+
+```bash
+docker run -p 8888:8888 ghcr.io/geojupyter/jupytergis:latest
+```
+
+Replace `latest` with a specific version number if you prefer.
+Docker build source is at <https://github.com/geojupyter/jupytergis-docker>.
+
 ## Documentation
 
 https://geojupyter.github.io/jupytergis

docs/user_guide/install.rst

@@ -16,3 +16,9 @@ Alternatively, you can install JupyterGIS with ``pip``
 .. code-block:: bash
 
    pip install jupytergis
+
+Or you can run JupyterGIS from a Docker image:
+
+.. code-block:: bash
+
+   docker run -p 8888:8888 ghcr.io/geojupyter/jupytergis:latest