added a more explanatory Readme

README.md

@@ -1,3 +1,16 @@
 # covid19_doorhandle
 
-inspired by  https://www.materialise.com/en/hands-free-door-opener but i am using openscad, plus i needed to adapt it to my doorhandles
+inspired by  https://www.materialise.com/en/hands-free-door-opener but i am
+using openscad, plus i needed to adapt it to my doorhandles
+
+rationale: places where people get in and out frequently, everyone touches the
+doorhandle, even with appropriated metallic coating of certain sorts (copper,
+silver etc) the handle is able to desinfect itself in a minimum time of 10 min,
+if passage is more often, lets try to not let the handle be touched then.
+
+Here comes this design, instead of using the hand, the forearm is used to make
+lever on the handle and to pull the door closed (if you need to push, you can
+also use more easily your body).
+
+now on thigieverse : https://www.thingiverse.com/thing:4233677
+