Add information to install libffi-dev, needed for python-mirobo (home-assistant#3172)

olskar · Landrash · commit 6baa22dba183 · 2017-08-13T10:10:52.000+02:00
* Add information to install libffi-dev, needed for python-mirobo

* Update vacuum.xiaomi.markdown
diff --git a/source/_components/vacuum.xiaomi.markdown b/source/_components/vacuum.xiaomi.markdown
@@ -20,6 +20,12 @@ Current supported features are `turn_on`, `pause`, `stop`, `return_to_home`, `tu
 
 Follow the pairing process using your phone and Mi-Home app. From here you will be able to retrieve the token from a SQLite file inside your phone.
 
+Before you begin you need to install `libffi-dev` by running the command below. This is needed for `python-mirobi` to be installed correctly. 
+
+```bash
+apt-get install libffi-dev
+```
+
 <p class='note warning'>
 If your Home Assistant installation is running in a [Virtualenv](/docs/installation/virtualenv/#upgrading-home-assistant), make sure you activate it by running the commands below.</p>
 
