tweaks: add a missing 'type' attribute to a <style> tag

To stop the W3 validator from complaining.

doc/faq.html

@@ -5,7 +5,7 @@
   <title>The GNU nano editor FAQ</title>
   <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
   <meta name="description" content="The genesis story of the nano editor, plus the solution to some common problems.">
-  <style>
+  <style type="text/css">
     .indented { margin-left: 2em; font-family: courier; font-size: 110%; }
   </style>
 </head>