Note errata fixed in fourth print

Author: marijnh

html/errata.html

@@ -18,9 +18,9 @@ <h1>Errata<div style="font-size: 70%"><a class="subtlelink" href="index.html">El
 page</a>. To report a problem that is not listed
 here, <a href="mailto:marijnh@gmail.com">send me an email</a>.</p>
 
-<p>Issues whose section title is followed by a superscript ¹ were
-fixed after the first print of the book, and will not be present in
-later prints. Those followed by ² were fixed in the third print.</p>
+<p>Issues whose section title is followed by a superscript number are
+only present up to the print denoted by that number. I.e. those
+followed by ² were fixed in the third print.</p>
 
 <h2>Introduction</h2>
 
@@ -44,7 +44,7 @@ <h2>Chapter 8</h2>
 
 <h2>Chapter 9</h2>
 
-<p><strong>Page 157</strong> (Repeating Parts of a Pattern): The
+<p><strong>Page 157</strong> (Repeating Parts of a Pattern³): The
 paragraph at the top of the page claims that <code>{,5}</code> is equivalent to
 <code>{0,5}</code> in a regular expression. This is not the case (you
 have to include the zero).</p>
@@ -117,7 +117,7 @@ <h2>Chapter 18</h2>
 
 <h2>Chapter 21</h2>
 
-<p><strong>Page 377</strong> (Long-Polling Support): In the second
+<p><strong>Page 377</strong> (Long-Polling Support³): In the second
 paragraph the <code>changesSince</code> parameter is incorrectly
 referred to as <code>changeSince</code> (singular).</p>