fix: Fixed typos

No actual code changes!

lib/index.js

@@ -6,29 +6,29 @@
  * @return {String}
  */
 function lessThanZeroError(p) {
-  return 'Percentile expect number >= 0 but given "' + p + '" and its type is "' + (typeof p) + '".';
+  return 'Expect percentile to be >= 0 but given "' + p + '" and its type is "' + (typeof p) + '".';
 }
 
 /**
- * Error message for case when percentile is grater than 100
+ * Error message for case when percentile is greater than 100
  *
  * @param {Number} p
  *
  * @return {String}
  */
-function graterThanHundredError(p) {
-  return 'Percentile expect number <= 100 but given "' + p + '" and its type is "' + (typeof p) + '".';
+function greaterThanHundredError(p) {
+  return 'Expect percentile to be <= 100 but given "' + p + '" and its type is "' + (typeof p) + '".';
 }
 
 /**
- * Error message for case when percentile is NaN
+ * Error message for case when percentile is not a number (NaN)
  *
  * @param {Number} p
  *
  * @return {String}
  */
 function nanError(p) {
-  return 'Percentile expect number but given "' + p + '" and its type is "' + (typeof p) + '".';
+  return 'Expect percentile to be a number but given "' + p + '" and its type is "' + (typeof p) + '".';
 }
 
 /**
@@ -52,7 +52,7 @@ function percentile(p, list, fn) {
   }
 
   if (p > 100) {
-    throw new Error(graterThanHundredError(p));
+    throw new Error(greaterThanHundredError(p));
   }
 
   list = list.slice().sort(function (a, b) {