fix: remove experimental model mention from GPT-5 release notes

Author: hannesrudolph

docs/update-notes/v3.25.10.mdx

@@ -24,8 +24,6 @@ We've added support for OpenAI's latest GPT-5 model family ([#6819](https://gith
 
 - **Verbosity Controls**: New settings to control model output detail levels (low, medium, high), allowing you to fine-tune response length and detail based on your needs
 
-- **Experimental Model**: Also includes the experimental `nectarine-alpha` model for testing cutting-edge capabilities
-
 All GPT-5 models support streaming responses for real-time interaction.
 
 > **📚 Documentation**: See [OpenAI Provider Guide](/providers/openai) for detailed information about GPT-5 models and verbosity settings.