Tweak comments

These comments only really make sense when one immediately follows the other, but since the rules around forced colors were added they’ve been separated.

Tweak the comments so they work when each rule stands alone.

src/govuk/components/header/_index.scss

@@ -36,7 +36,8 @@
   .govuk-header__logotype {
     display: inline-block;
 
-    // Add a gap between logo and any product name
+    // Add a gap after the logo in case it's followed by a product name. This
+    // gets removed later if the logotype is a :last-child.
     margin-right: govuk-spacing(1);
 
     // Prevent readability backplate from obscuring underline in Windows High
@@ -46,8 +47,8 @@
       color: linktext;
     }
 
-    // But remove it if there's nothing after the logo to keep hover and focus
-    // states neat
+    // Remove the gap after the logo if there's no product name to keep hover
+    // and focus states neat
     &:last-child {
       margin-right: 0;
     }