First set of 'motors' topics (#305)

* Start of 'motors' topics

* Draft the 'motor motion' side doc

* Add / update more topics

* Last blast of edits

* Capture some more edits

* Put in movement and steering details

docs/reference/motors/motor/clear-counts.md

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+# clear Counts
+
+Set all counters for the motor back to zero.
+
+```sig
+motors.largeA.clearCounts()
+```
+
+The counters for a motor are: **tacho**, **angle**, and **speed**. Each of these counters is set to start counting from `0` again. This is a way to begin new counts without having to reset the motor.
+
+## Example
+
+See if the motor turns the same number of times for each of two count periods. Run the motor connected to port **A** twice for 10 seconds and compare the tacho counts.
+
+```blocks
+let tachoCount = 0;
+motors.largeA.reset()
+motors.largeA.setSpeed(50)
+loops.pause(10000)
+tachoCount = motors.largeA.tacho()
+motors.largeA.clearCounts()
+motors.largeA.setSpeed(50)
+loops.pause(10000)
+if (tachoCount == motors.largeA.tacho()) {
+    brick.showString("Motor turns equal.", 1)
+} else {
+    brick.showString("Motor turns NOT equal.", 1)
+}
+motors.largeA.stop()
+```
+
+## See also
+
+[tacho](/reference/motors/motor/tacho), [angle](/reference/motors/motor/angle),
+[speed](/reference/motors/motor/speed), [reset](/reference/motors/motor/reset)