Adding slow-connection-quality parameter (#20803)

* Adding slow-connection-quality parameter

* Tweak description for chromium based

Author: deven96

src/content/docs/images/transform-images/transform-via-url.mdx

@@ -123,6 +123,10 @@ You must specify at least one option. Options are comma-separated (spaces are no
 
 <Render file="sharpen" />
 
+### `slow-connection-quality`
+
+<Render file="slow-connection-quality" />
+
 ### `trim`
 
 <Render file="trim" />
@@ -165,4 +169,4 @@ If Custom Cache Keys are used for the origin image, the origin image might not b
 
 Resized images follow the same caching rules as the original image they were resized from, except the minimum cache time is one hour. If you need images to be updated more frequently, add `must-revalidate` to the `Cache-Control` header. Resizing supports cache revalidation, so we recommend serving images with the `Etag` header. Refer to the [Cache docs for more information](/cache/concepts/cache-control/#revalidation).
 
-Cloudflare Images does not support purging resized variants individually. URLs starting with `/cdn-cgi/` cannot be purged. However, purging of the original image's URL will also purge all of its resized variants.
+Cloudflare Images does not support purging resized variants individually. URLs starting with `/cdn-cgi/` cannot be purged. However, purging of the original image's URL will also purge all of its resized variants.

src/content/partials/images/slow-connection-quality.mdx

@@ -0,0 +1,43 @@
+---
+{}
+---
+import { Tabs, TabItem } from "~/components"
+
+:::note[Note]
+At the moment, this setting only works directly with [image transformations](/images/transform-images/).
+:::
+
+Allows overriding `quality` value whenever a slow connection is detected.
+
+Available options are same as [quality](/images/transform-images/transform-via-url/#quality).
+
+<Tabs>
+  <TabItem label="URL format">
+    ```js
+    slow-connection-quality=50
+    ```
+  </TabItem>
+  <TabItem label="URL format alias">
+  ```js
+  scq=50
+  ```
+  </TabItem>
+</Tabs>
+
+Detecting slow connections is currently only supported on Chromium-based browsers such as Chrome, Edge, and Opera.
+
+You can enable any of the following client hints via HTTP in a header
+
+```txt
+accept-ch: rtt, save-data, ect, downlink
+```
+
+slow-connection-quality applies whenever any of the following is true and the client hint is present:
+
+- [rtt](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/RTT): Greater than 150ms.
+
+- [save-data](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Save-Data): Value is "on".
+
+- [ect](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/ECT): Value is one of `slow-2g|2g|3g`.
+
+- [downlink](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Downlink): Less than 5Mbps.