Add embedding via 404 page

README.md

@@ -4,6 +4,20 @@ A simplified, SVG-only QR code generator based on QRCode.js. This lightweight li
 
 Try it out at [OnlyQR Demo](https://onlyqr.0n8.de).
 
+## Embedding via URL
+
+Everything after the domain becomes the QR code content, and the page shows only the QR code, scaled to fit:
+
+```html
+<iframe src="https://onlyqr.0n8.de/hello-world" width="200" height="200" style="border:0"></iframe>
+<iframe src="https://onlyqr.0n8.de/https%3A%2F%2Fexample.com?color=ff0000" width="200" height="200" style="border:0"></iframe>
+```
+
+- `?color=` takes a hex value without `#` (e.g. `ff0000`) or a CSS colour name. The default is `004c93`.
+- Use `encodeURIComponent(text)` for the path, so that `?`, `#`, `%` and `/` in your text come through unchanged.
+- Any other query parameters are treated as part of the text.
+- This is handled by `404.html` on the static host, so it only works in iframes (not `<img src>`), and the HTTP status is 404.
+
 ## Changes from Original QRCode.js
 
 - Removed Canvas and Table rendering methods