Merge branch 'tricopter-yaw-docs' of git://github.com/sherlockflight/cleanflight-dev into sherlockflight-tricopter-yaw-docs

Conflicts:
	docs/Controls.md

docs/Controls.md

@@ -43,3 +43,38 @@ The stick positions are combined to activate different functions:
 
 Download a graphic [cheat sheet](https://multiwii.googlecode.com/svn/branches/Hamburger/MultiWii-StickConfiguration-23_v0-5772156649.pdf) with Tx stick commands (the latest version can always be found 
 [here](https://code.google.com/p/multiwii/source/browse/#svn%2Fbranches%2FHamburger)).
+
+## Yaw control
+
+While arming/disarming with sticks, your yaw stick will be moving to extreme values. In order to prevent your craft
+from trying to yaw during arming/disarming while on the ground, your yaw input will not cause the craft to yaw when the
+throttle is LOW (i.e. below the `min_check` setting).
+
+For tricopters, you may want to retain the ability to yaw while on the ground, so that you can verify that your tail
+servo is working correctly before takeoff. You can do this by setting `tri_unarmed_servo` to `1` on the CLI (this is the
+default). If you are having issues with your tail rotor contacting the ground during arm/disarm, you can set this to
+`0` instead. Check this table to decide which setting will suit you:
+
+<table>
+    <tr>
+        <th colspan="5">Is yaw control of the tricopter allowed?</th>
+    </tr>
+    <tr>
+        <th></th><th colspan="2">Disarmed</th><th colspan="2">Armed</th>
+    </tr>
+    <tr>
+        <th></th><th>Throttle low</th><th>Throttle normal</th><th>Throttle low</th><th>Throttle normal</th>
+    </tr>
+    <tr>
+        <td rowspan="2">tri_unarmed_servo = 0</td><td>No</td><td>No</td><td>No</td><td>Yes</td>
+    </tr>
+    <tr>
+        <td>No</td><td>No</td><td>No</td><td>Yes</td>
+    </tr>
+    <tr>
+        <td rowspan="2">tri_unarmed_servo = 1</td><td>Yes</td><td>Yes</td><td>Yes</td><td>Yes</td>
+    </tr>
+    <tr>
+        <td>Yes</td><td>Yes</td><td>Yes</td><td>Yes</td>
+    </tr>
+</table>