compiling Basic example

[bfilin]

I'm getting a couple of issues while testing the Basic example, perhaps I'm doing something wrong:

1. Seeing the following error while compiling Basic:
   /usr/local/lib/urweb/ur/world/github.ur:126:8: (to 126:20) Unbound structure Monad

   Fixed by adding $/monad to world/lib.urp

2. examples/README.md says:
   To run Basic example: copy basic_in.urp.in to basic_in.urp and fill in your GitHub application details.

   However, examples directory has basic_in.ur.in file (not the basic_in.urp.in).

   Perhaps examples/README.md should say:
   To run Basic example: copy basic_in.ur.in to basic_in.ur and fill in your GitHub application details.

   I tested it by copying basic_in.ur.in to basic_in.ur and setting my GitHub client_id and client_secret in basic_in.ur, after that Basic compiles fine and OAuth test is performed against GitHub.