chore: fix wrong word and white space (#167)

Author: Jehun Seem

src/multiply.js

@@ -4,7 +4,7 @@ export default multiply
  * This method will perform multiply 2 numbers.
  *
  * @param {Number} num1 - first number
- * @param {Number} num2 - second  number
+ * @param {Number} num2 - second number
  * @return {Number} - Result of multiplying first number by second number
  */
 function multiply(num1, num2) {

src/startsWith.js

@@ -3,7 +3,7 @@ export default startsWith
 /**
  * Original Source: http://stackoverflow.com/a/646631/5954939
  *
- * This method will return a bollean indicating whether a string starts with a given input.
+ * This method will return a boolean indicating whether a string starts with a given input.
  *
  * @param {String} str - The string to validate against
  * @param {String} head - The input to match with str substring

src/subtract.js

@@ -5,7 +5,7 @@ export default Subtract
  * @Description This method will perform Subtract operation.
  *
  * @param {Number} num1 - first number for Subtraction
- * @param {Number} num2 - second  number for Subtraction
+ * @param {Number} num2 - second number for Subtraction
  * @return {Number} - Result of Subtraction
  */
 function Subtract(num1, num2) {