Add link to protobuf extension by murdos

Author: fmbenhassine

README.md

@@ -174,6 +174,7 @@ There are many other uses cases where Easy Random can be useful, you can find a
 
 * [JUnit extension](https://glytching.github.io/junit-extensions/randomBeans): Use Easy Random to generate random data in JUnit tests (courtesy of [glytching](https://github.com/glytching))
 * [Vavr extension](https://github.com/xShadov/easy-random-vavr-extension): This extension adds support to randomize [Vavr](https://github.com/vavr-io/vavr) types (courtesy of [xShadov](https://github.com/xShadov))
+* [Protocol Buffers extension](https://github.com/murdos/easy-random-protobuf): This extension adds support to randomize [Protocol Buffers](https://developers.google.com/protocol-buffers) generated types (courtesy of [murdos](https://github.com/murdos))
 
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