Add documentation for the client-side DNS cache options

doc/tor.1.txt

@@ -929,11 +929,30 @@ The following options are useful only for clients (that is, if
         Tells exits that, if a host has both an IPv4 and an IPv6 address,
         we would prefer to connect to it via IPv6. (IPv4 is the default.) +
 +
-    NOTE: Although this option allows you to specify an IP address other than
-    localhost, you should do so only with extreme caution.  The SOCKS
-    protocol is unencrypted and (as we use it) unauthenticated, so exposing
-    it in this way could leak your information to anybody watching your
-    network, and allow anybody to use your computer as an open proxy.
+       NOTE: Although this option allows you to specify an IP address
+       other than localhost, you should do so only with extreme caution.
+       The SOCKS protocol is unencrypted and (as we use it)
+       unauthenticated, so exposing it in this way could leak your
+       information to anybody watching your network, and allow anybody
+       to use your computer as an open proxy.
+    **CacheIPv4DNS**;;
+        Tells the client to remember IPv4 DNS answers we receive from exit
+        nodes via this connection. (On by default.)
+    **CacheIPv6DNS**;;
+        Tells the client to remember IPv6 DNS answers we receive from exit
+        nodes via this connection.
+    **CacheDNS**;;
+        Tells the client to remember all DNS answers we receive from exit
+        nodes via this connection.
+    **UseIPv4Cache**;;
+        Tells the client to use any cached IPv4 DNS answers we have when making
+        requests via this connection. (On by default.)
+    **UseIPv6Cache**;;
+        Tells the client to use any cached IPv6 DNS answers we have when making
+        requests via this connection.
+    **UseDNSCache**;;
+        Tells the client to use any cached DNS answers we have when making
+        requests via this connection.
 
 **SOCKSListenAddress** __IP__[:__PORT__]::
     Bind to this address to listen for connections from Socks-speaking