Fix Waypoint Nest Anchor in Paragraph Code Guidance

Added comments to delineate which areas of the code should be modified since we were seeing a lot of confusion on the tests not passing when the `p` tag was at the bottom of the page.
Closes #3805

seed/challenges/html5-and-css.json

@@ -1156,9 +1156,11 @@
         "</style>",
         "",
         "<h2 class=\"red-text\">CatPhotoApp</h2>",
+        "<!--Do not alter code above this line-->",
         "",
         "<a href=\"http://www.freecatphotoapp.com\">cat photos</a>",
         "",
+        "<!--Do not alter code below this line-->",
         "<img class=\"smaller-image thick-green-border\" src=\"https://bit.ly/fcc-relaxing-cat\">",
         "",
         "<p class=\"red-text\">Kitty ipsum dolor sit amet, shed everywhere shed everywhere stretching attack your ankles chase the red dot, hairball run catnip eat the grass sniff.</p>",