Merge pull request #179 from PaulBernier/patch-1

Fix formatting of screw specifications in README

Author: lewisxhe

shell/README.MD

@@ -11,5 +11,5 @@
 
 ![style2](./images/style3.jpg)
 
-Housing screw specifications: M1.5*5
-PCB mounting screw specifications: M2*4
+Housing screw specifications: M1.5\*5
+PCB mounting screw specifications: M2\*4