[Speed] Add API link and example for HTTP2 multiplexing (#20315)

* Adds link and API example

* Adds dashboard instructions

* Apply suggestions from code review

Co-authored-by: marciocloudflare <[email protected]>

---------

Co-authored-by: marciocloudflare <[email protected]>

Author: angelampcosta

src/content/docs/speed/optimization/protocol/http2-to-origin.mdx

@@ -4,7 +4,7 @@ title: HTTP/2 to Origin
 
 ---
 
-import { FeatureTable } from "~/components"
+import { FeatureTable, Details, Render } from "~/components"
 
 A protocol is a set of rules governing the exchange or transmission of data between devices. One of the most important protocols that run on the human-computer interaction layer, where applications can access the network services, is HTTP (Hypertext Transfer Protocol).
 
@@ -29,7 +29,36 @@ If you wish to disable HTTP/2 to Origin, you can follow these steps:
 
 Cloudflare’s HTTP/2 multiplexing to origin reduces active connections by pooling many requests into fewer TCP connections. If a request arrives and the current connection has not reached the stream limit, Cloudflare reuses the existing connection. If the limit has not been reached, Cloudflare may open additional connections to handle more requests. Because multiplexing reuses fewer TCP connections, the overall number of active connections to your origin will typically be lower, which is often helpful for systems sensitive to connection overhead. During surges (like failovers), Cloudflare scales connections by first using available streams, then opening new ones as needed.
 
-Connection multiplexing is enabled by default on Free, Pro and Business zones and uses up to 100 concurrent streams by default. For Enterprise plans, you can explicitly configure the maximum number of concurrent streams (often called the “multiplexing ratio”) for a zone.
+### Configuration
+
+Connection multiplexing is enabled by default on Free, Pro and Business zones and uses up to 100 concurrent streams by default. Enterprise plans can explicitly configure the maximum number of concurrent streams (often called the “multiplexing ratio”) for a zone in the dashboard or via API.
+
+<Details header="Dashboard">
+
+1. Log in to the [Cloudflare dashboard](https://dash.cloudflare.com/login) and select your account.
+2. Choose the domain that will use HTTP/2 to Origin.
+3. Select **Speed > Optimization**.
+4. Open the **Protocol Optimization** tab. 
+5. Under **HTTP/2 to Origin**, select **Configure** and adjust the stream settings as needed.
+
+</Details>
+
+<Details header="API">
+
+```bash
+curl --request PATCH \
+https://api.cloudflare.com/client/v4/zones/<ZONE_ID>/settings/origin_h2_max_streams \
+--header 'Content-Type: application/json' \
+--header "X-Auth-Email: <CLOUDFLARE_EMAIL>" \
+--header "X-Auth-Key: <CLOUDFLARE_API_KEY>" \
+--data '{
+      "value": <int>
+    }'
+```
+
+Refer to the [API documentation](/api/python/resources/zones/subresources/settings/methods/edit/) for more information.
+
+</Details>
 
 :::note
 If your origin does not support multiplexing, enabling HTTP/2 to origin may result in 5xx errors, particularly 520s.