Polishing

README.md

@@ -4,7 +4,7 @@ logstash-gelf
 [![Join the chat at https://gitter.im/mp911de/logstash-gelf](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/mp911de/logstash-gelf?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
 
 [![Build Status](https://api.travis-ci.org/mp911de/logstash-gelf.svg)](https://travis-ci.org/mp911de/logstash-gelf)
-[![codecov](https://codecov.io/gh/mp911de/logstash-gelf/branch/master/graph/badge.svg)](https://codecov.io/gh/mp911de/logstash-gelf)
+[![codecov](https://codecov.io/gh/mp911de/logstash-gelf/branch/main/graph/badge.svg)](https://codecov.io/gh/mp911de/logstash-gelf)
 [![Maven Central](https://maven-badges.herokuapp.com/maven-central/biz.paluch.logging/logstash-gelf/badge.svg)](https://maven-badges.herokuapp.com/maven-central/biz.paluch.logging/logstash-gelf)
 
 Provides logging to logstash using the Graylog Extended Logging Format ([GELF](http://www.graylog2.org/resources/gelf/specification) 1.0 and 1.1) for using with:
@@ -446,4 +446,4 @@ License
 Contributing
 ------------
 Github is for social coding: if you want to write code, I encourage contributions through pull requests from forks of this repository. 
-Create Github tickets for bugs and new features and comment on the ones that you are interested in and take a look into [CONTRIBUTING.md](https://github.com/mp911de/logstash-gelf/blob/master/.github/CONTRIBUTING.md)
+Create Github tickets for bugs and new features and comment on the ones that you are interested in and take a look into [CONTRIBUTING.md](https://github.com/mp911de/logstash-gelf/blob/main/.github/CONTRIBUTING.md)