address merge_soft duplicate files (TheAlgorithms#1612)

Here the old file merge_sort_fastest is renamed to unknown_sort. Because it is not merge sort algorithm.

Comments are updated accordingly.

Author: bardia52

sorts/merge_sort_fastest.py renamed to sorts/unknown_sort.py

@@ -1,6 +1,5 @@
 """
-Python implementation of the fastest merge sort algorithm.
-Takes an average of 0.6 microseconds to sort a list of length 1000 items.
+Python implementation of a sort algorithm.
 Best Case Scenario : O(n)
 Worst Case Scenario : O(n^2) because native python functions:min, max and remove are already O(n)
 """