docs: modernize 2 examples

docs/examples.rst

@@ -185,9 +185,9 @@ nested.py:
 .. code-block:: python
 
     import os
-    import mitogen.utils
+    import mitogen
 
-    @mitogen.utils.run_with_router
+    @mitogen.main()
     def main(router):
         mitogen.utils.log_to_file()
 

docs/index.rst

@@ -351,6 +351,7 @@ usual into the slave process.
         os.system('tar zxvf my_app.tar.gz')
 
 
+    @mitogen.main()
     def main(broker):
         if len(sys.argv) != 2:
             print(__doc__)
@@ -359,10 +360,6 @@ usual into the slave process.
         context = mitogen.ssh.connect(broker, sys.argv[1])
         context.call(install_app)
 
-    if __name__ == '__main__' and mitogen.is_master:
-        import mitogen.utils
-        mitogen.utils.run_with_broker(main)
-
 
 Event-driven IO
 ###############