Fix typo in README regarding GitHub Copilot CLI

Author: netgio

README.md

@@ -79,7 +79,7 @@ Bare `specify self upgrade` executes immediately, matching the no-prompt behavio
 
 ### 3. Establish project principles
 
-Launch your coding agent in the project directory. Most agents expose spec-kit as `/speckit.*` slash commands; Codex CLI in skills mode uses `$speckit-*` instead; Github Copilot CLI uses `/agents` to select the agent or address it directly in a prompt.
+Launch your coding agent in the project directory. Most agents expose spec-kit as `/speckit.*` slash commands; Codex CLI in skills mode uses `$speckit-*` instead; GitHub Copilot CLI uses `/agents` to select the agent or address it directly in a prompt.
 
 Use the **`/speckit.constitution`** command to create your project's governing principles and development guidelines that will guide all subsequent development.