Clarify wording for default API endpoint info

Updated the text to clarify that the default API endpoint is a pre-deployed instance, improving readability and user understanding.

index.html

@@ -347,7 +347,7 @@
         class="text-center mt-6 text-gray-500 text-sm animate-fade-in-delay-3"
       >
         <p>
-          Default API Endpoint is a pre-deployed instance of
+          The default API endpoint is a pre-deployed instance of
           <a
             href="https://github.com/xixu-me/DeepLX"
             target="_blank"