[Stream] Add troubleshooting reference for Media Transformation error codes

Adds a troubleshooting reference for Media Transformation error codes.

Author: bkrebsbach

src/content/docs/stream/reference/index.mdx

@@ -0,0 +1,11 @@
+---
+title: Reference
+pcx_content_type: overview
+sidebar:
+  group:
+    hideIndex: true
+---
+
+import { DirectoryListing } from "~/components";
+
+<DirectoryListing />

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

@@ -0,0 +1,29 @@
+---
+pcx_content_type: troubleshooting
+title: Troubleshooting
+sidebar:
+  order: 8
+---
+
+## Error responses from Media Transformations
+
+When resizing fails, the response body contains an error message explaining the reason, as well as the `Cf-Resized` header containing `err=code`:
+
+- 9401 — The required options are missing or are invalid. Refer to [Options](/stream/transform-videos/#options) for supported arguments.
+- 9402 — The video was too large or the origin server did not respond as expected. Refer to [Source video requirements](/stream/transform-videos/#source-video-requirements) for more information.
+- 9404 — The video does not exist on the origin server or the URL used to transform the video is wrong. Verify the video exists and check the URL.
+- 9406 & 9419 — The video URL is a non-HTTPS URL or the URL has spaces or unescaped Unicode. Check your URL and try again.
+- 9407 — A lookup error occurred with the origin server's domain name. Check your DNS settings and try again.
+- 9408 — The origin server returned an HTTP 4xx status code and may be denying access to the video. Confirm your video settings and try again.
+- 9412 — The origin server returned a non-video, for example, an HTML page. This usually happens when an invalid URL is specified or server-side software has printed an error or presented a login page.
+- 9504 — The origin server could not be contacted because the origin server may be down or overloaded. Try again later.
+- 9509 — The origin server returned an HTTP 5xx status code. This is most likely a problem with the origin server-side software, not the transformation.
+- 9517 & 9523 — Internal errors. Please contact support if you encounter these errors.
+
+---
+
+## Limits
+
+- Maximum input file size is 100 MB. Maximum duration of input video is 10 minutes.
+- Media Transformations is not compatible with [Bring Your Own IP (BYOIP)](/byoip/).
+- Input video should be an MP4 with H.264 encoded video and AAC or MP3 encoded audio. Other formats may work but are untested.

src/content/docs/stream/transform-videos/index.mdx

@@ -126,9 +126,9 @@ Specifies the filename to use in the returned Content-Disposition header. If not
 
 ## Source video requirements
 
-Input video must be less than 100MB.
-
-Input video should be an MP4 with H.264 encoded video and AAC or MP3 encoded audio. Other formats may work but are untested.
+- Input video must be less than 100MB.
+- Input video should be an MP4 with H.264 encoded video and AAC or MP3 encoded audio. Other formats may work but are untested.
+- Origin must support either HTTP HEAD and range requests, and must return a Content-Range header.
 
 ## Limitations