Corrected the Python Doctest command in equilibrium_index_in_array.py script (TheAlgorithms#11212)

Co-authored-by: Indrajeet Mishra <indrajeetmishra@thecoddiwompler.local>

Author: thecoddiwompler

data_structures/arrays/equilibrium_index_in_array.py

@@ -3,7 +3,7 @@
 Reference: https://www.geeksforgeeks.org/equilibrium-index-of-an-array/
 
 Python doctest can be run with the following command:
-python -m doctest -v equilibrium_index.py
+python -m doctest -v equilibrium_index_in_array.py
 
 Given a sequence arr[] of size n, this function returns
 an equilibrium index (if any) or -1 if no equilibrium index exists.