Add documentation for the commit message prompt type to the README

Author: robertpiosik

README.md

@@ -36,7 +36,9 @@ Code Web Chat (CWC) is a free and open-source, privacy-first **AI coding toolkit
 
 ## Introduction
 
-In the world of AI coding, agents like Claude Code or Codex rely on "Function Calling" (where the AI asks "the harness" to read a file, waits for the tool to respond, then reads another). CWC flips this by letting you provide context files upfront. Iterate on instructions 10X faster, without polluting the context window!
+In the world of AI coding, agents like Claude Code or Codex rely on "Function Calling" (where the AI asks "the harness" to read a file, waits for the tool to respond, then reads another). CWC flips this by letting you provide context files upfront.
+
+Iterate on instructions 10X faster, without polluting the context window!
 
 **Prompt types:**
 
@@ -81,13 +83,23 @@ In the world of AI coding, agents like Claude Code or Codex rely on "Function Ca
 
 ```
 <files>[current file tree selection]</files>
-<system>[output format instructions]</system>
+<system>[response format instructions]</system>
 Find all files building modules of the following task's scope:
 [user-typed prompt]
 ```
 
 </details>
 
+<details>
+<summary>Commit message</summary>
+
+```
+<files>[staged files diffs and contents]</files>
+[commit message instructions]
+```
+
+</details>
+
 <details>
 <summary>No context</summary>