Update 05. New Contact, Default flow Out of office hours notification…

…s.md

aaded info on Regular expression including image

docs/3. Product Features/10. Others/05. New Contact, Default flow Out of office hours notifications.md

@@ -75,3 +75,21 @@ There may be a requirement to send automated responses, when contact send any ke
 1. It will not work for new contacts, when they message it for the very first time.
 1. If beneficiary enters any keyword of any flow, then that particular flow will execute, not the flow selected in `out of`  `Hours of operation` .
 1. The `out of Hours of operation`flow will be executed only once in a day for each contact,
+
+## Regular Expression Flow
+
+<img width="497" alt="image" src="https://github.com/user-attachments/assets/7caf579a-cd23-42e7-bcf5-ecbf5b0a90b4"/>
+
+1. Regular expressions (or regex) helps you find and work with text, based on patterns.
+2. Thus making it a powerful tool for searching, replacing, or validating information in a large set of 
+  data.
+
+4. For a simple regular expression to match a 10-digit number, you can use: “[0-9]{10}”
+
+5. You can read and play around with regular expressions [here](https://regexr.com/)
+
+6. The selected flow will trigger when end-users aren’t in any flow, their message doesn’t match any keyword, and their message matches the regular expression defined under **Regular 
+ Expression.**
+
+
+