Update sustainability section to explain prompt caching is enabled by including selected context files with instructions in a single prompt

Author: robertpiosik

README.md

@@ -39,7 +39,7 @@ Code Web Chat (CWC) is a free and open-source, privacy-first **AI coding toolkit
 
 ## Sustainability 🌱
 
-Zero [function calling](https://developers.openai.com/api/docs/guides/function-calling/) design and update/pick recency file ordering enables [prompt caching](https://developers.openai.com/api/docs/guides/prompt-caching/) across tasks. Make your chatbot quotas last longer or lower token costs by up to 90%. Enable blazing fast local inference!
+Because selected context files are included with your instructions in a single prompt, CWC enables heavy [prompt caching](https://developers.openai.com/api/docs/guides/prompt-caching/) utilization, across tasks. Make your chatbot quotas last longer or lower token costs by up to 90%. Enable blazing fast local inference!
 
 ## Enabling autofill