Update 2. Working with Distinct Values and Sets.md

Author: ortizfram

Introduction to MongoDB in Python/2. Working with Distinct Values and Sets.md

@@ -137,3 +137,10 @@ ratio = n_in_or_after / (n_in_or_after + n_before)
 print(ratio)
 ```
     0.84
+
+## # finding substring w/ $regex
+`"$regex"` every result that contains : "x"
+![image](https://user-images.githubusercontent.com/51888893/204360355-f2c31962-e37c-4257-91a1-caf9d896cda7.png)
+
+### # $regex flags  beginning,ending,escaping
+![image](https://user-images.githubusercontent.com/51888893/204361075-06e60e1d-2979-41c9-82f7-82ac9a38b737.png)