Clarify PublishServerDescriptor even more

doc/tor.1.txt

@@ -867,15 +867,17 @@ is non-zero):
     multiple times to bind to multiple addresses/ports.
 
 **PublishServerDescriptor** **0**|**1**|**v1**|**v2**|**v3**|**bridge**|**hidserv**,**...**::
-    This option specifies which descriptors Tor will publish. You can
+    This option specifies which descriptors Tor will publish when acting as
+    a relay or hidden service. You can
     choose multiple arguments, separated by commas.
  +
-    If set to 0, Tor will not publish its
+    If this option is set to 0, Tor will not publish its
     descriptors to any directories. (This is useful if you're testing
     out your server, or if you're using a Tor controller that handles directory
     publishing for you.) Otherwise, Tor will publish its descriptors of all
     type(s) specified. The default is "1",
-    which means "publish the appropriate descriptors to the authorities".
+    which means "if running as a server or a hidden service, publish the
+    appropriate descriptors to the authorities".
 
 **ShutdownWaitLength** __NUM__::
     When we get a SIGINT and we're a server, we begin shutting down: