Add dictionary merge explanation

Author: braboj

examples/04_operators/operators_dict.py

@@ -1,3 +1,10 @@
+# Merging and updating dictionaries
+# -----------------------------------------------------------------------------
+# Python 3.9 introduced the | and |= operators to combine dictionaries. The | 
+# operator creates a new dictionary containing keys from both operands, while
+# |= updates the dictionary on the left in place. This provides a concise
+# alternative to using the update() method or ** unpacking for merging.
+
 a = {'a': 1, 'b': 2, 'c': 3}
 b = {'d': 4, 'e': 5}