some pyodide docs

docs/cli.ipynb

@@ -221,7 +221,8 @@
     "| `--federated-extensions` | paths to folders, `pip`/`conda` packages with extensions [see note](#conda-packages) |                               |                             |\n",
     "| `--ignore-sys-prefix`    | don't copy any contents, such as install labextensions, from `sys.prefix`            | `False`                       |                             |\n",
     "| `--settings-overrides`   | additional settings overrides to enable                                              |                               |                             |\n",
-    "| `--piplite-wheels`       | additional wheels to make available                                                  |                               |                             |"
+    "| `--piplite-wheels`       | additional wheels to make available                                                  |                               |                             |\n",
+    "| `--pyodide`              | the path or URL of a pyodide release                                                 |                               |                             |"
    ]
   },
   {
@@ -751,7 +752,7 @@
    "source": [
     "### pyolite wheels\n",
     "\n",
-    "_Prebuilt Lab Extension_ developers who wish to include wheels for use with pyolite may use this command to pre-index wheels they wish to distribute. This can be useful if a package needs upstream patches, etc."
+    "_Prebuilt Lab Extension_ developers who wish to include wheels for use with [pyolite](./kernels/pyolite.md) may use this command to pre-index wheels they wish to distribute. This can be useful if a package needs upstream patches, etc."
    ]
   },
   {
@@ -769,6 +770,18 @@
     "!jupyter lite pip index --help"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "id": "49f781c1-3588-4608-a560-318f3507969f",
+   "metadata": {},
+   "source": [
+    "### pyodide\n",
+    "\n",
+    "[Pyodide](https://pyodide.org) is a WebAssembly distribution of CPython and powers the [pyolite](./kernels/pyolite.md) kernel. At nearly 200mb, compressed,  a full pyodide distribution includes both the Python interpreter and key anchor packages from the scientific computing stack. Parts of it are fetched, as needed, by the user's browser, from the official pyodide CDN.\n",
+    "\n",
+    "The `--pyodide` CLI option (and `pyodide_url` config option) allow for fetching either a compressed pyodide `.bz2`, or folder containing such an archive's contents. This might be from the official [pyodide release page](https://github.com/pyodide/pyodide/releases), a nightly or PR asset, or otherwise custom build. Once fetched, it is copied to the output folder, and configured correctly in `jupyter-lite.json`."
+   ]
+  },
   {
    "cell_type": "markdown",
    "id": "a60ecfe7-0973-4a81-9d0c-d85f9f960d3a",

docs/configuring.md

@@ -151,6 +151,24 @@ Package Index (PyPI). This behavior can be disabled via `jupyter-lite.json`:
 }
 ```
 
+## Pyodide
+
+Beneah custom wheels are the raw JS and WebAssembly parts of `pyolite` provided by
+[pyodide](https://pyodide.org). A custom `pyodide.js`, along with its `packages.json`
+and the rest of its assets, such as might be downloaded via the
+[`--pyodide` CLI option](./cli.ipynb#pyodide), can also be configured. This can be
+either relative to the `lite_dir`, or as an absolute path.
+
+```json
+"jupyter-config-data": {
+  "litePluginSettings": {
+    "@jupyterlite/pyolite-kernel-extension:kernel": {
+      "pyodideUrl": "./path/to/custom/pyodide/pyodide.js"
+    }
+  }
+}
+```
+
 ## LaTeX
 
 Rendering $\LaTeX$ is generally handled in a special way when compared with most other

docs/doit.ipynb

@@ -172,7 +172,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.8.10"
+   "version": "3.9.7"
   }
  },
  "nbformat": 4,