Added one more example (#144)

* Added one more example

Added one more example to explain the recursion stack of merge sort to provide in-depth knowledge of the algorithm.
Also added best case, worst case, and average time complexity.

* Update en/Sorting Algorithms/Merge Sort.md

Co-authored-by: David Leal <halfpacho@gmail.com>

Co-authored-by: David Leal <halfpacho@gmail.com>

Author: ayush26sharma

en/Sorting Algorithms/Merge Sort.md

@@ -12,13 +12,17 @@ Given an array of n elements, write a function to sort the array
 
 #### Time Complexity
 
-`O(n log n)`
+```
+Best case - O(n log n)
+Average - O(n log n)
+Worst case - O(n log n)
+```
 
 #### Space Complexity
 
 `O(n)`
 
-#### Example
+#### Example 1
 
 ```
 arr = [1, 3, 9, 5, 0, 2]  
@@ -31,6 +35,30 @@ Recursively call merge sort function for both these halves which will provide so
 Now merge both these halves to get the sorted array [0, 1, 2, 3, 5, 9]
 ```
 
+#### Example 2
+
+```
+arr = [1, 9, 2, 5, 7, 3, 6, 4]  
+
+Divide the array into two halves [1, 9, 2, 5] and [7, 3, 6, 4]
+
+As you can see that the above two halves are not yet sorted, so divide both of them into two halves again.
+
+This time we get four arrays as [1, 9], [2, 5], [7, 3] and [6, 4].
+
+We see that the last two arrays are again not sorted, so we divide them again into two halves and we will get [7], [3], [6], and [4].
+
+Since an array of a single element is sorted, we now have all the arrays sorted, now we only need to merge them appropriately.
+
+First, the arrays of one element will be merged as they were divided in last, and are at top of the recursion stack, so we get [3,7] and [4,6].
+
+Now the merge will occur accordingly to the recursion stack, [1, 9] and [2, 5] will be merged and will make [1, 2, 5, 9].
+
+Similarly [3, 7] and [4, 6] will be merged and made [3, 4, 6, 7].
+
+At the next stack level [1, 2, 5, 9] and [3, 4, 6, 7] will be merged and we will get the final sorted array as [1, 2, 3, 4, 5, 6, 7, 9].
+```
+
 #### Code Implementation Links
 
 - [Java](https://github.com/TheAlgorithms/Java/blob/master/Sorts/MergeSort.java)