Add CyberDefenders link to Blue Team section (#36)

* Add CyberDefenders link to Blue Team section

Another great platform for our blue team guys to learn networking , reversing malware and many more things

* alphabetize

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Co-authored-by: Yan Shoshitaishvili <yans@yancomm.net>

Author: w3nch

README.md

@@ -210,6 +210,7 @@ The chals below are listed with recommended ones first, then the rest in alphabe
 ### Blue Team / DFIR
 
 - [Blue Team Labs Online](https://blueteamlabs.online/)
+- [CyberDefenders](https://cyberdefenders.org/)
 - [LetsDefend](https://app.letsdefend.io/)
 
 ### Unsorted