Docs typo

[Alain Armand]

At the bottom of the docs you have:

Compile with:

$ dune build example/simple_middleware/main.ml

Here we also use the ability of Opium to generate a cmdliner term to run your app. Run your executable with -h to see the options that are available to you. For example:

# run in debug mode on port 9000
$ dune exec dune build example/simple_middleware/main.exe -- -p 9000 -d

I think the last line should be on of dune exec or dune build. Also, running with the -h flag gets you, assuming that command is correct:

~/Github/opium-0.20.0 main                                                                                              3.0.1
❯ dune build example/simple_middleware/main.re


~/Github/opium-0.20.0 main                                                                                              3.0.1
❯ dune exec example/simple_middleware/main.exe -- -p 9000 -h
Reject UA: option `-h' needs an argument
Usage: Reject UA [OPTION]... 
Try `Reject UA --help' for more information.

What options should we be passing?

Thank you.