Fix typos and elaborate note.

Author: skynavga

cssom/Overview.html

@@ -1885,8 +1885,8 @@ <h3 id="css-declaration-blocks"><span class="secno">6.5 </span>CSS Declaration B
 
   <p class="note">The serialization of an empty CSS declaration block is the empty string.</p>
 
-  <p class="note">The serialization of an non-empty CSS declaration block does not including any surrounding whitespace, i.e., no whitepsace
-  before the first property name and no whitespace after the final semicolon delimiter that follows the last property value..</p>
+  <p class="note">The serialization of an non-empty CSS declaration block does not include any surrounding whitespace, i.e., no whitepsace appears
+  before the first property name and no whitespace appears after the final semicolon delimiter that follows the last property value.</p>
 
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cssom/cssom-source

@@ -1489,8 +1489,8 @@
 
   <p class="note">The serialization of an empty CSS declaration block is the empty string.</p>
 
-  <p class="note">The serialization of an non-empty CSS declaration block does not including any surrounding whitespace, i.e., no whitepsace
-  before the first property name and no whitespace after the final semicolon delimiter that follows the last property value..</p>
+  <p class="note">The serialization of an non-empty CSS declaration block does not include any surrounding whitespace, i.e., no whitepsace appears
+  before the first property name and no whitespace appears after the final semicolon delimiter that follows the last property value.</p>
 
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