[2005] move some periods

A long multi-sentence parenthetical remark may be strange
embedded in a single sentence.

doc/guide/bind10-guide.xml

@@ -1953,12 +1953,12 @@ what is XfroutClient xfr_client??
       both UDP and TCP, and both IPv6 and IPv4; for TCP requests,
       however, it terminates the TCP connection immediately after
       each single request has been processed.  Clients cannot reuse the
-      same TCP connection for multiple requests (This is a current
-      implementation limitation of <command>b10-ddns</command>;
-      while RFC 2136 doesn't specify anything about such reuse of TCP
+      same TCP connection for multiple requests. (This is a current
+      implementation limitation of <command>b10-ddns</command>.
+      While RFC 2136 doesn't specify anything about such reuse of TCP
       connection, there is no reason for disallowing it as RFC 1035
       generally allows multiple requests sent over a single TCP
-      connection.  BIND 9 supports such reuse).
+      connection.  BIND 9 supports such reuse.)
     </para>
 
     <para>