DOC Add basic documentation (#50)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

README.md

@@ -1,3 +1,26 @@
 # pyodide-recipes-mirror
 
 Collections of package recipes for Pyodide
+
+## Adding a new package
+
+> Note: Use Python 3.12 or upper to run the following commands.
+
+To add a new package, create a package recipe in the `packages` directory.
+You can start by creating a boilerplate recipe with the following command:
+
+```bash
+$ pip install pyodide-build
+$ pyodide skeleton pypi <package-name>
+```
+
+This will create a new directory in the `packages/` directory with the package name.
+You can then edit the `meta.yaml` file in the package directory to add build scripts
+and other metadata including the dependencies.
+
+See the [Pyodide documentation](https://pyodide.org/en/stable/development/new-packages.html)
+for more information on creating package recipes.
+
+## Maintainer information
+
+See [MAINTAINERS.md](docs/MAINTAINERS.md) for information on how to maintain this repository.

docs/MAINTAINERS.md

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+# Maintainer information
+
+## How packages are built and tested in CI
+
+When a PR is opened, the GHA workflow will build submitted packages and run tests on them.
+It only builds the packages that have been modified in the PR, and their dependenciesto reduce the build time.
+See [tools/calc_diff.py](../tools/calc_diff.py) for the logic used to determine which packages to build.
+
+When the PR is merged, the GHA workflow will build all packages in the repository and run tests on them.
+Optionally, you can trigger a full build by adding the `[full build]` commit message to the PR.
+
+The packages are always built with the tip-of-tree commit of Pyodide, fetching it directly from the CDN.
+This is to ensure that the packages in this repository are always compatible with the latest version of Pyodide.
+
+## Releasing a new package set and updating the Pyodide distribution
+
+Adding a new tag to the repository will trigger a release of the package set.
+It is recommended to use the calendar versioning scheme for tags, e.g. `20240810`.
+
+```
+git tag 20240810
+git push origin 20240810
+```
+
+__(THIS IS NOT YET IMPLEMENTED)__
+
+After the release is done, you can update the package set in the Pyodide distribution
+by updating the `Makefile.envs` file in the pyodide/pyodide repository.
+
+## Building and testing packages locally
+
+To build and test packages locally, you need to prepare the necessary tools and dependencies.
+
+- compatible Python version
+- pyodide-build
+- emscripten
+- selenium (for testing)
+
+if you need to use a tip-of-tree commit of Pyodide,
+you can install it manually from the following url:
+
+```
+pyodide xbuildenv install --url http://pyodide-cache.s3-website-us-east-1.amazonaws.com/xbuildenv/dev/xbuildenv.tar.bz2
+```