Readme update. Virtual Machine use remark

PrzemekWirkus · PrzemekWirkus · commit 86fb5ce24184 · 2016-03-02T23:14:27.000Z
diff --git a/README.md b/README.md
@@ -531,4 +531,5 @@ OK
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 # Known issues
+* Users reported issues while using ```mbed-ls``` on VM (Virtual Machines).
 * [mbedls fails to list devices on OS X El Capitan](https://github.com/ARMmbed/mbed-ls/issues/38).
