Update English documents

doc/FAQ.html

@@ -615,9 +615,9 @@ Which?
    </dt>
    <dd>
     <p>
-     Set the environment variable HTTP_PROXY or use the option
-     setting panel (<q>o</q> key). For example, if you want to use
-     port 8000 of proxy.example.org, specify
+     Set the environment variables HTTP_PROXY, HTTPS_PROXY, GOPHER_PROXY
+     and FTP_PROXY, or use the option setting panel (<q>o</q> key). For
+     example, if you want to use port 8000 of proxy.example.org, specify
     </p>
 <pre>
     http://proxy.example.org:8000/
@@ -636,7 +636,8 @@ Which?
     firefox %s &
 </pre>
     <p>
-     (if you are using Firefox).
+     (if you are using Firefox). Note that %s is replaced with the URL
+     when invoking.
     </p>
    </dd>
    <dt>

doc/MANUAL.html

@@ -860,8 +860,8 @@ The two equivalents to the meta-key are pressing simultaneously the ALT-key or p
      M
     </td>
     <td>
-     Browse current document using external browser (prefix 2 or 3 to
-     invoke alternate configured browsers, e.g. 3 M)
+     Browse current document using external browser (prefix 2, 3, ...,
+     or 9 to invoke alternate configured browsers, e.g. 3 M)
     </td>
    </tr>
    <tr>
@@ -1725,8 +1725,8 @@ The two equivalents to the meta-key are pressing simultaneously the ALT-key or p
      M
     </td>
     <td>
-     Browse current document using external browser (prefix 2 or 3 to
-     invoke alternate configured browsers, e.g. 3 M)
+     Browse current document using external browser (prefix 2, 3, ...,
+     or 9 to invoke alternate configured browsers, e.g. 3 M)
     </td>
    </tr>
    <tr>