Update README.md

README.md

@@ -85,4 +85,4 @@ the top side of the Harmonic Board. This introduces a potential for large amount
 substrate when some force is applied to the display. This is the main mechanical weak point of the device.
 
 It might be beneficial to change the layout so the display is soldered to the bottom side of
-the Harmonic Board. Together with the double sided tape for the battery this should be save as well.
+the Harmonic Board. Together with the double sided tape for the battery this should be safe as well.