Build: Document missing docker.sock on OSX (#8766)

README.md

@@ -77,6 +77,16 @@ Iceberg also has modules for adding Iceberg support to processing engines:
 * `iceberg-mr` contains an InputFormat and other classes for integrating with Apache Hive
 * `iceberg-pig` is an implementation of Pig's LoadFunc API for Iceberg
 
+---
+**NOTE** 
+
+The tests require Docker to execute. On MacOS (with Docker Desktop), you might need to create a symbolic name to the docker socket in order to be detected by the tests:
+
+```
+sudo ln -s $HOME/.docker/run/docker.sock /var/run/docker.sock
+```
+---
+
 ### Engine Compatibility
 
 See the [Multi-Engine Support](https://iceberg.apache.org/multi-engine-support/) page to know about Iceberg compatibility with different Spark, Flink and Hive versions.