Added a note about unit testing

&#1052;&#1077;&#1090;&#1086; &#1058;&#1088;&#1072;&#1112;&#1082;&#1086;&#1074;&#1089;&#1082;&#1080; · &#1052;&#1077;&#1090;&#1086; &#1058;&#1088;&#1072;&#1112;&#1082;&#1086;&#1074;&#1089;&#1082;&#1080; · commit eacf6c30cd31 · 2020-01-22T21:29:31.000+01:00
diff --git a/Arrays/rotate_array.py b/Arrays/rotate_array.py
@@ -65,9 +65,12 @@ def rotate_array_2(arr, k, right = True):
             j += 1
 
             # add the previous element on this position
+            curr, arr[idx] = arr[idx], curr
+            '''same as
             temp = curr
             curr = arr[idx]
             arr[idx] = temp
+            '''
 
         i += 1
 
diff --git a/README.md b/README.md
@@ -80,6 +80,7 @@ print(name_of_solution_1(test_val))
 print(name_of_solution_2(test_val))
 ```
 
+*Note that here I'm using the **simplest** way of testing, printing the results using the [print](https://docs.python.org/3/library/functions.html#print) method. Why? Because I think that the bigger part of the users of this repo isn't familiar with [unit testing](https://en.wikipedia.org/wiki/Unit_testing) and I wanted this part to be intuitive. Btw, I'm strongly recommending to use some unit testing framework for this kind of testing. The Python Standard Library contains a **great** framework for unit testing called [unittest](https://docs.python.org/3/library/unittest.html), or you can install some third-party unit testing framework like [pytest](https://docs.pytest.org/en/latest/).*
 
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