Adding dark&light versions of first-api-call.md thumbnail (#1827)

Author: Reeray

docs/inference-providers/guides/first-api-call.md

@@ -1,5 +1,10 @@
 # Your First Inference Provider Call
 
+<div class="flex justify-center">
+    <img class="block dark:hidden" src="https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/inference-providers-guides/first-api-call-thumbnail-light.png"/>
+    <img class="hidden dark:block" src="https://huggingface.co/datasets/huggingface/documentation-images/resolve/main/inference-providers-guides/first-api-call-thumbnail-dark.png"/>
+</div>
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 In this guide we're going to help you make your first API call with Inference Providers.
 
 Many developers avoid using open source AI models because they assume deployment is complex. This guide will show you how to use a state-of-the-art model in under five minutes, with no infrastructure setup required.
@@ -243,4 +248,4 @@ Now that you've seen how easy it is to use AI models, you might wonder:
 - How does billing work?
 - What other models can you use?
 
-Continue to the next guide to understand the provider ecosystem and make informed choices about authentication and billing. 
+Continue to the next guide to understand the provider ecosystem and make informed choices about authentication and billing.