fix: updates doco to include missing command (#268)

Signed-off-by: Anthony D. Mays <[email protected]>

Author: anthonydmays

lesson_06/README.md

@@ -23,6 +23,7 @@ HW_VERSION=D
 ```
 2. Run the program to determine the expression you must implement.
 ```bash
+npm install
 npm run compile
 npm start
 ```

lesson_06/expression/src/lesson6.test.ts

@@ -39,7 +39,7 @@ describe("Lesson6Test", () => {
 
   test("testAdd_works", () => {
     // Act
-    const result = calculator.add(1, 2);
+    const result = calculator.add(2, 3);
 
     // Assert
     expect(result).toBe(3);