docs: add inflection/inflection-3-productivity (#319)

Author: Lookoff-AIMLAPI

docs/SUMMARY.md

@@ -150,6 +150,7 @@
     * [Ring 2.6 1T](api-references/text-models-llm/inclusionAI/ring-2.6-1t.md)
   * [Inflection](api-references/text-models-llm/Inflection/README.md)
     * [3 Pi](api-references/text-models-llm/Inflection/inflection-3-pi.md)
+    * [3 Productivity](api-references/text-models-llm/Inflection/inflection-3-productivity.md)
   * [Meituan](api-references/text-models-llm/Meituan/README.md)
     * [Longcat 2.0](api-references/text-models-llm/Meituan/longcat-2.0.md)
   * [Meta](api-references/text-models-llm/Meta/README.md)