docs(readme): update feature list for clarity and accuracy (#1431)

Refined feature descriptions in README:
- Clarified tool calling and privacy features
- Updated interactive chat and token efficiency wording
- Added scriptable Lua API highlight

Improves transparency and better communicates capabilities.

Signed-off-by: Tomas Slusny <slusnucky@gmail.com>

Author: deathbeam

README.md

@@ -19,11 +19,12 @@ https://github.com/user-attachments/assets/8cad5643-63b2-4641-a5c4-68bc313f20e6
 CopilotChat.nvim brings GitHub Copilot Chat capabilities directly into Neovim with a focus on transparency and user control.
 
 - 🤖 **Multiple AI Models** - GitHub Copilot (including GPT-4o, Gemini 2.5 Pro, Claude 4 Sonnet, Claude 3.7 Sonnet, Claude 3.5 Sonnet, o3-mini, o4-mini) + custom providers (Ollama, Mistral.ai). The exact list of available models depends on your [GitHub Copilot settings](https://github.com/settings/copilot/features) and the models provided by GitHub's API.
-- 🔧 **Tool Calling** - LLM can use workspace functions (file reading, git operations, search) with your explicit approval
-- 🔒 **Explicit Control** - Only shares what you specifically request - no background data collection
-- 📝 **Interactive Chat** - Rich UI with completion, diffs, and quickfix integration
+- 🔧 **Tool Calling** - LLM can call workspace functions (file reading, git operations, search) with your explicit approval
+- 🔒 **Privacy First** - Only shares what you explicitly request - no background data collection
+- 📝 **Interactive Chat** - Interactive UI with completion, diffs, and quickfix integration
 - 🎯 **Smart Prompts** - Composable templates and sticky prompts for consistent context
-- ⚡ **Efficient** - Smart token usage with tiktoken counting and history management
+- ⚡ **Token Efficient** - Resource replacement prevents duplicate context, history management via tiktoken counting
+- 🔗 **Scriptable** - Comprehensive Lua API for automation and headless mode operation
 - 🔌 **Extensible** - [Custom functions](https://github.com/CopilotC-Nvim/CopilotChat.nvim/discussions/categories/functions) and [providers](https://github.com/CopilotC-Nvim/CopilotChat.nvim/discussions/categories/providers), plus integrations like [mcphub.nvim](https://github.com/ravitemer/mcphub.nvim)
 
 # Installation