Update README.md to reference main branch instead of removed master

Author: MichalPrincNXP

README.md

@@ -246,7 +246,7 @@ To install the Python infrastructure for eRPC see instructions in the [erpc_pyth
 
 ## Code providing
 
-Repository on Github contains two main branches. __Master__ and __develop__. Code is developed on __develop__ branch. Release version is created via merging __develop__ branch into __master__ branch.
+Repository on Github contains two main branches: __main__ and __develop__. Code is developed on __develop__ branch. Release version is created via merging __develop__ branch into __main__ branch.
 
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