Updating 9520 as unsupported format (cloudflare#19414)

Author: deven96

src/content/docs/images/reference/troubleshooting.mdx

@@ -40,7 +40,7 @@ When resizing fails, the response body contains an error message explaining the
 * 9504, 9505, & 9510 — The origin server could not be contacted because the origin server may be down or overloaded. Try again later.
 * 9523 — The `/cdn-cgi/image/` resizing service could not perform resizing. This may happen when an image has invalid format. Use correctly formatted image and try again.
 * 9524 — The `/cdn-cgi/image/` resizing service could not perform resizing. This may happen when an image URL is intercepted by a Worker. As an alternative you can [resize within the Worker](/images/transform-images/transform-via-workers/). This can also happen when using a `pages.dev` URL of a [Cloudflare Pages](/pages/) project. In that case, you can use a [Custom Domain](/pages/configuration/custom-domains/) instead.
-* 9511 — The image format is not supported. Refer to [Supported formats and limitations](/images/transform-images/) to learn about supported input and output formats.
+* 9520 — The image format is not supported. Refer to [Supported formats and limitations](/images/transform-images/) to learn about supported input and output formats.
 * 9522 — The image exceeded the processing limit. This may happen briefly after purging an entire zone or when files with very large dimensions are requested. If the problem persists, contact support.
 * 9422, 9424, 9516, 9517, 9518, 9522 & 9523 — Internal errors. Please contact support if you encounter these errors.