Increase overall width to max 1000px

The maximum width is currently set to 600px, while this works, it could
easily have an increased width (say 1000px), which would improve
readability of long code snippets.

_sass/jekyll-theme-hacker.scss

@@ -21,7 +21,7 @@ body {
 
 .container {
   width: 90%;
-  max-width: 600px;
+  max-width: 1000px;
   margin: 0 auto;
 }