feat: implement BMI calculation function and add example usage

Author: CatchingKiyoko

Sprint-2/3-mandatory-implement/1-bmi.js

@@ -16,4 +16,10 @@
 
 function calculateBMI(weight, height) {
     // return the BMI of someone based off their weight and height
-}
+    const heightSquared = height * height; // square the height
+    const bmi = weight / heightSquared; // calculate BMI by dividing weight by height squared
+    const roundedBmi = bmi.toFixed(1);  // round the result to 1 decimal place
+    return roundedBmi; // return the rounded BMI value
+}
+console.log(calculateBMI(70, 1.73)); // Example usage: should return 23.4
+console.log(calculateBMI(80, 1.8)); // Example usage: should return 24.7