doc/protocol: remove UTF-8 explanation

These days, this is common knowledge, and doesn't need a lengthy
explanation.

Author: MaxKellermann

doc/protocol.xml

@@ -59,15 +59,7 @@
 
       <para>
         All data between the client and the server is encoded in
-        UTF-8. (Note: In UTF-8 all standard ansi characters, 0-127 are
-        the same as in standard ansi encoding.  Also, no ansi character
-        appears in any multi-byte characters.  So, you can use
-        standard C functions like <function>strlen</function>, and
-        <function>strcpy</function> just fine with UTF-8 encoded
-        strings. For example: <returnvalue>OK</returnvalue> encoded in
-        UTF-8 is simply <returnvalue>OK</returnvalue>.  For more
-        information on UTF-8:
-        <ulink url="http://www.cl.cam.ac.uk/~mgk25/unicode.html#utf-8"/>)
+        UTF-8.
       </para>
     </section>