Plant watering system (#419)

* added youtube movie

* plant watering system

* added project entry

docs/projects/plant-watering/make.md

@@ -0,0 +1,24 @@
+# Make
+
+
+## The pump
+
+Follow the instructions on the move to build a mini water-pump using a @boardname@ and a servo.
+
+https://youtu.be/jANCdtkJAKY
+
+
+## The soil moisture sensor
+
+Follow the instructions of the [soil moisture project](/projects/soil-moisture) to build a soil moisture sensor 
+and upload the code to your @boardname@. 
+
+The final wiring should look like this:
+
+![](/static/mb/projects/plant-watering/make.jpg)
+
+### ~button /projects/plant-watering/code
+
+Code
+
+### ~