Update challenge description for css classes in html elements

challenges/01-front-end-development-certification/html5-and-css.json

@@ -711,7 +711,7 @@
         "Remember that you can attach classes to HTML elements by using <code>class=\"your-class-here\"</code> within the relevant element's opening tag.",
         "Remember that CSS class selectors require a period at the beginning like this:",
         "<blockquote>.blue-text {<br>&nbsp;&nbsp;color: blue;<br>}</blockquote>",
-        "But also remember that class declarations don't use a period, like this:",
+        "But remember you don't need to use a period when attaching classes to an html element:",
         "<code>&#60;h2 class=\"blue-text\"&#62;CatPhotoApp&#60;/h2&#62;</code>",
         "Apply the <code>red-text</code> class to your <code>h2</code> and <code>p</code> elements."
       ],