Clarify HTML entity example

We replaced the double quotation marks example with an ampersand example, using the opening line to Edward Lear's poem 'The Owl and the Pussy-cat'.  The double quotation marks do not strictly speaking require an HTML entity in the previous example whereas an ampersand always requires an HTML entity.

We also removed the 'em' because we already have 'strong' as a follow on from a prior point and adding 'em' does not add anything to the learning of this particular example.

Author: leenacha

html/lesson1/tutorial.md

@@ -272,16 +272,14 @@ One way is to use **HTML entities**. These are made up of an ampersand, a name,
 
 You can also use a numerical format to produce special characters. [Here's a list](http://htmlandcssbook.com/extras/html-escape-codes/) of some common entities.
 
-Add a small rhyme to your page, wrapped with quotes using HTML entities.
+Add a small rhyme to your page, in which the first sentence says "The Owl & the Pussy-cat" instead of "The Owl and the Pussy-cat" using HTML entities for the ampersand: `&`.
 
 ```html
 <div>
   <p>
     <strong>
-      <em>
-       &quot;A wise old owl sat on an oak;  The more he saw the less he spoke; <br>
-       The less he spoke the more he heard; Why aren't we like that wise old bird?&quot;
-      </em>
+       "The Owl &amp; the Pussy-cat went to sea <br> 
+        In a beautiful pea-green boat"
     </strong>
   </p>
   <small>&mdash; nursery rhyme</small>