Update README with more info

README.md

@@ -36,8 +36,6 @@ Then your site will be published under https://{USERNAME}.github.io/{DEMO_REPO_N
 
 You can pre-install extra packages for xeus-python by adding them to the ``environment.yml`` file.
 
-Only ``no-arch`` packages from ``conda-forge`` and packages from ``emscripten-forge`` can be installed.
-
 For example, if you want to create a JupyterLite deployment with NumPy and Matplotlib pre-installed, you would need to edit the ``environment.yml`` file as following:
 
 ```yml
@@ -49,3 +47,8 @@ dependencies:
   - numpy
   - matplotlib
 ```
+
+Only ``no-arch`` packages from ``conda-forge`` and ``emscripten-forge`` can be installed.
+- **How do I know if a package is ``no-arch`` on ``conda-forge``?** ``no-arch`` means that the package is OS-independent, usually pure-python packages are ``no-arch``. To check if your package is ``no-arch`` on ``conda-forge``, check if the "Platform" entry is "no-arch" in the https://beta.mamba.pm/channels/conda-forge?tab=packages page. If your package is not ``no-arch`` but is a pure Python package, then you should probably update the feedstock to turn your package into a ``no-arch`` one.
+![](noarch.png)
+- **How do I know if my package is on ``emscripten-forge``?** You can see the list of packages pubished on ``emscripten-forge`` [here](https://beta.mamba.pm/channels/emscripten-forge?tab=packages). In case your package is missing, or it's not up-to-date, feel free to open an issue or a PR on https://github.com/emscripten-forge/recipes.