Update README.md

Co-authored-by: Kamalpreet Kaur <38219887+kamal-kaur04@users.noreply.github.com>

Author: 2 people

README.md

@@ -1,6 +1,6 @@
 # Java-selenium-browserstack
 ---
-Master branch contains testNG samples with browserstack-java-sdk.
+`main` branch contains TestNG samples with browserstack-java-sdk.
 
 ![BrowserStack Logo](https://d98b8t1nnulk5.cloudfront.net/production/images/layout/logo-header.png?1469004780)