Update custom-costs.mdx (#16781)

deleted extra {}s in example

Author: kathayl

src/content/docs/ai-gateway/configuration/custom-costs.mdx

@@ -31,17 +31,17 @@ Custom costs will appear in the logs with an underline, making it easy to identi
 In this example, if you have a negotiated price of $1 per million input tokens and $2 per million output tokens, include the `cf-aig-custom-cost` header as shown below.
 
 ```bash title="Request with custom cost"
-curl https://gateway.ai.cloudflare.com/v1/{{account_id}}/{{gateway_id}}/openai/chat/completions \
+curl https://gateway.ai.cloudflare.com/v1/{account_id}/{gateway_id}/openai/chat/completions \
   --header 'Authorization: Bearer $TOKEN' \
   --header 'Content-Type: application/json' \
   --header 'cf-aig-custom-cost: {"per_token_in":0.000001,"per_token_out":0.000002}' \
-  --data ' {{
+  --data ' {
         "model": "gpt-4o-mini",
         "messages": [
-          {{
+          {
             "role": "user",
             "content": "When is Cloudflare’s Birthday Week?"
-          }}
+          }
         ]
-      }}'
+      }'
 ```