[guide] fix "bad" comment to be actually bad

HenrYxZ · ljharb · commit 06998522e1f4 · 2018-04-06T14:53:46.000-03:00
diff --git a/README.md b/README.md
@@ -2267,7 +2267,7 @@ Other Style Guides
 
     ```javascript
     // bad
-    // is current tab
+    //is current tab
     const active = true;
 
     // good
