Update .github/copilot-instructions.md

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

Author: kmruiz

.github/copilot-instructions.md

@@ -31,7 +31,7 @@ and MongoDB Atlas accounts. It is built using TypeScript, Node.js and the offici
 - Use classes for stateful components and functions for stateless pure logic.
 - Use dependency injection to provide dependencies between components.
 - Avoid using global variables as much as possible.
-- New functionalities MUST be under test.
+- New functionality MUST be under test.
   - Tools MUST HAVE integration tests.
   - Tools MUST HAVE unit tests.
   - Tools MAY HAVE accuracy tests.