Added PHP code test to readme

Author: dcsl-alexis

README.md

@@ -1,6 +1,14 @@
 # Interview Code Challenges
 Here you will find some different code challenges options for interviewing at One Beyond.
 
+## .NET code tests
+1. [.net Engineer - Library API functionality](/.NET/library/README.md#net-engineer-challenge)
+2. [Mobile Engineer - Mobile Library Application](/.NET/library/README.md#mobile-engineer-challenge)
+
+## PHP code tests
+1. [PHP Engineer - Library API functionality](/PHP/library-api-php/README.md)
+
+
 ## Node tests
 1. [Implement the martian robots game](/node/martian-robots/instructions.md)
 2.  [Implement the tennis score game](/node/tennis-score/instructions.md)
@@ -9,9 +17,6 @@ Here you will find some different code challenges options for interviewing at On
 1. [Build a phone catalogue](/react/phone-catalogue/instructions.md)
 2. [Build an app around a mysterious API](/react/mysterious-api/instructions.md)
 
-## .NET code tests
-1. [.net Engineer - Library API functionality](/.NET/library/README.md#net-engineer-challenge)
-2. [Mobile Engineer - Mobile Library Application](/.NET/library/README.md#mobile-engineer-challenge)
 
 ## Java tests
 1. [Implement the martian robots game](/java/martian-robots/instructions.md)