docs: add openai/gpt-5.3-chat (#360)

Author: Lookoff-AIMLAPI

docs/SUMMARY.md

@@ -257,6 +257,7 @@
     * [Gpt 5 Codex](api-references/text-models-llm/openai/gpt-5-codex.md)
     * [Gpt 5 Image](api-references/text-models-llm/openai/gpt-5-image.md)
     * [Gpt 5.2 Chat](api-references/text-models-llm/openai/gpt-5.2-chat.md)
+    * [Gpt 5.3 Chat](api-references/text-models-llm/openai/gpt-5.3-chat.md)
   * [Perplexity](api-references/text-models-llm/perplexity/README.md)
     * [Sonar](api-references/text-models-llm/perplexity/sonar.md)
     * [Sonar Pro](api-references/text-models-llm/perplexity/sonar-pro.md)