Reference wiki and remove duplicated information

ROMFS/px4fmu_common/mixers/README

@@ -4,55 +4,8 @@ PX4 mixer definitions
 Files in this directory implement example mixers that can be used as a basis
 for customisation, or for general testing purposes.
 
-Mixer basics
-------------
-
-Mixers combine control values from various sources (control tasks, user inputs,
-etc.) and produce output values suitable for controlling actuators; servos,
-motors, switches and so on.
-
-An actuator derives its value from the combination of one or more control
-values. Each of the control values is scaled according to the actuator's
-configuration and then combined to produce the actuator value, which may then be
-further scaled to suit the specific output type.
-
-Internally, all scaling is performed using floating point values. Inputs and
-outputs are clamped to the range -1.0 to 1.0.
-
-control    control   control
-   |          |         |
-   v          v         v
- scale      scale     scale
-   |          |         |
-   |          v         |
-   +-------> mix <------+
-              |
-            scale
-              |
-              v
-             out
-
-Scaling
--------
-
-Basic scalers provide linear scaling of the input to the output.
-
-Each scaler allows the input value to be scaled independently for inputs
-greater/less than zero. An offset can be applied to the output, and lower and
-upper boundary constraints can be applied. Negative scaling factors cause the
-output to be inverted (negative input produces positive output).
-
-Scaler pseudocode:
-
-if (input < 0)
-    output = (input * NEGATIVE_SCALE) + OFFSET
-else
-    output = (input * POSITIVE_SCALE) + OFFSET
-
-if (output < LOWER_LIMIT)
-    output = LOWER_LIMIT
-if (output > UPPER_LIMIT)
-    output = UPPER_LIMIT
+For a detailed description of the mixing architecture and examples see:
+https://pixhawk.org/dev/mixing
 
 Syntax
 ------
@@ -65,6 +18,9 @@ Each file may define more than one mixer; the allocation of mixers to actuators
 is specific to the device reading the mixer definition, and the number of
 actuator outputs generated by a mixer is specific to the mixer.
 
+For example: each simple or null mixer is assigned to outputs 1 to x
+in the order they appear in the mixer file.
+
 A mixer begins with a line of the form
 
 	<tag>: <mixer arguments>