Fix description of missing-semicolon-after-character-reference error

The previous description was incorrect: `&notin` without a semicolon
will not be parsed as "∉" because `&notin` without a semicolon is not
included in the first column of the named character references table.

Author: squeek502

source

@@ -126702,14 +126702,18 @@ dictionary <dfn dictionary>StorageEventInit</dfn> : <span>EventInit</span> {
      <td><dfn data-x="parse-error-missing-semicolon-after-character-reference">missing-semicolon-after-character-reference</dfn>
      <td>
       <p>This error occurs if the parser encounters a <span data-x="syntax-charref">character
-      reference</span> that is not terminated by a U+003B (;) <span>code point</span>. Usually the
-      parser behaves as if character reference is terminated by the U+003B (;) code point; however,
-      there are some ambiguous cases in which the parser includes subsequent code points in the
-      character reference.</p>
-
-      <p class="example">For example, <code data-x="">&amp;not;in</code> will be parsed as "<code
-      data-x="">&not;in</code>" whereas <code data-x="">&amp;notin</code> will be parsed as "<code
-      data-x="">&notin;</code>".</p>
+      reference</span> that is not terminated by a U+003B (;) <span>code point</span>.
+      The parser behaves the same as if the character reference is terminated by the U+003B
+      (;) code point.</p>
+
+      <p class="note">Most <span>named character references</span> require a terminating U+003B
+      (;) <span>code point</span>. Those that don't might get resolved as a longer named <span
+      data-x="syntax-charref">character reference</span> in certain ambiguous scenarios.</p>
+
+      <p class="example">For example, <code data-x="">&amp;notin</code> will be parsed as "<code
+      data-x="">&not;in</code>", i.e., the same as if the input were <code
+      data-x="">&amp;not;in</code>, whereas <code data-x="">&amp;notin;</code> will be parsed as
+      "<code data-x="">&notin;</code>".</p>
 
     <tr>
      <td><dfn data-x="parse-error-missing-whitespace-after-doctype-public-keyword">missing-whitespace-after-doctype-public-keyword</dfn>