Adding small statement about WSL.

README.md

@@ -1,5 +1,13 @@
 # readthedocs
 This repository contains the top-level documentation for NJOY21. It is best viewed at [docs.njoy21.io](https://docs.njoy21.io).
 
+## Building
+This documentation uses [Sphinx](https://sphinx-doc.org) to build and serve the documentation. You can build and serve the documentation locally
+
+```console
+sphinx-autobuild docs docs/_build/html --port=4001
+```
+Then just go to [localhost:4001](localhost:4001) and you can see the documentation.
+
 ## LICENSE
 This software is copyrighted by Los Alamos National Laboratory and distributed according to the conditions in the accompanying [LICENSE](LICENSE) file.

docs/install.rst

@@ -41,6 +41,10 @@ build system and `git <https://git-scm.com>`__ for version control.
 -  `CMake 3.2+ <https://cmake.org/>`__
 -  `git 2.1+ <https://git-scm.com>`__
 
+Windows
+-------
+When building on Windows, we only support using the [Windows Subsystem for Linux](https://docs.microsoft.com/en-us/windows/wsl/). The build system is the same.
+
 Build Process
 =============