plugin: correct working directory comment

Reported by Joe Doyle of Trail of Bits.

plugin/client.go

@@ -457,9 +457,8 @@ func openClientConnection(name, protocol string) (*clientConnection, error) {
 		cmd.Stderr = os.Stderr
 	}
 
-	// We don't want the plugins to rely on the working directory for anything
-	// as different clients might treat it differently, so we set it to an empty
-	// temporary directory.
+	// Avoid running plugins in the client's working directory, as it might
+	// differ between clients.
 	cmd.Dir = os.TempDir()
 
 	if err := cmd.Start(); err != nil {