Update .github/copilot-instructions.md

Co-authored-by: Copilot <[email protected]>

Author: ryanzhang-oss

.github/copilot-instructions.md

@@ -109,7 +109,7 @@ A breadcrumb is a collaborative scratch pad that allow the user and agent to get
 3. Structure the breadcrumb file with these required sections:
    1. **Understand the Problem**:
    * Read the relevant parts of the codebase.
-   * List of referred material like domain knowledge files, specification files, URLs and summary of what is was used for.
+   * List of referred material like domain knowledge files, specification files, URLs and summary of what it was used for.
    * Browse public API documentation for up-to-date info.
    * Propose 2–3 implementation options with pros and cons.
    * Ask clarifying questions about product requirements.