Add a word about it in README

Author: KevinFairise2

README.md

@@ -60,6 +60,12 @@ To get the list of available tasks
 
 Run any `-h` on any of the available tasks for more information
 
+## MacOS support
+
+The `aws.create-vm` task should allow you to spin up a MacOS instance using `-o macos` flag. Note that spinning such an instance is expensive because it requires a dedicated host. When you have one running please reuse it instead of creating new instances every time you need it. The cleaner will automatically get rid of the dedicated hosts.
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+
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 ## Troubleshooting
 
 ### Environment and configuration