Add note about flag emoji display

Author: aphillips

index.html

@@ -1492,7 +1492,7 @@ <h3 id="char_def">Characters and character encoding basics</h3>
         </tr>
 
 
-    <tr><td colspan="8" style="text-align:left">Some of the [=visual text units=] require more than one character. This phrase consists of seven characters. The emoji characters use some of the more unusual features of Unicode. Specifically, <span class="codepoint"><bdi lang="en">&#x2764;</bdi><code class="uname">U+2764 HEAVY BLACK HEART</code></span> is followed by <span class="codepoint"><img src="./images/FE0F.png" alt="U+FE0F"><code class="uname">U+FE0F VARIATION SELECTOR-16</code></span> in order to display as an emoji variant, while the flag of Switzerland is formed using a pair of emoji flag characters.</td></tr>
+    <tr><td colspan="8" style="text-align:left">Some of the [=visual text units=] require more than one character. This particular phrase consists of seven characters because these emoji characters use some of the more unusual features of Unicode. <span class="codepoint"><bdi lang="en">&#x2764;</bdi><code class="uname">U+2764 HEAVY BLACK HEART</code></span> is followed by <span class="codepoint"><img src="./images/FE0F.png" alt="U+FE0F"><code class="uname">U+FE0F VARIATION SELECTOR-16</code></span> in order to display as an emoji variant, while the flag of Switzerland is formed using a pair of emoji flag characters. (Note: on some browsers, the "flag" might display as a grapheme cluster with the letters <kbd>CH</kbd>. These are still treated by the browser as a single grapheme cluster!)</td></tr>
 
         <tr>
             <th width="15%">[=Encoded character=]</th>