docs: fix broken text image (#2202)

Fixes: #2125
Currently, the text-image is broken on mobile for /en/docs/guides/event-loop-timers-and-nexttick
But it should not be so.

Author: Aditya Srivastava

layouts/css/_base.styl

@@ -67,7 +67,7 @@ pre
   border-radius 3px
   padding 0.75em 1.2em
   font-size 0.8em
-  white-space pre-wrap
+  white-space pre
   color $light-gray3
   overflow-x auto