linkedlist: correct grammar in comments

PR-URL: https://github.com/nodejs/node/pull/14546
Reviewed-By: Vse Mozhet Byt <vsemozhetbyt@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>

lib/internal/linkedlist.js

@@ -5,13 +5,13 @@ function init(list) {
   list._idlePrev = list;
 }
 
-// show the most idle item
+// Show the most idle item.
 function peek(list) {
   if (list._idlePrev === list) return null;
   return list._idlePrev;
 }
 
-// remove a item from its list
+// Remove an item from its list.
 function remove(item) {
   if (item._idleNext) {
     item._idleNext._idlePrev = item._idlePrev;
@@ -25,18 +25,18 @@ function remove(item) {
   item._idlePrev = null;
 }
 
-// remove a item from its list and place at the end.
+// Remove an item from its list and place at the end.
 function append(list, item) {
   if (item._idleNext || item._idlePrev) {
     remove(item);
   }
 
-  // items are linked  with _idleNext -> (older) and _idlePrev -> (newer)
+  // Items are linked  with _idleNext -> (older) and _idlePrev -> (newer).
   // Note: This linkage (next being older) may seem counter-intuitive at first.
   item._idleNext = list._idleNext;
   item._idlePrev = list;
 
-  // the list _idleNext points to tail (newest) and _idlePrev to head (oldest)
+  // The list _idleNext points to tail (newest) and _idlePrev to head (oldest).
   list._idleNext._idlePrev = item;
   list._idleNext = item;
 }