add details on how to run generated code

[cglotr]

Fixes #362

Added some details on how to run the generated code. I was having a bad time following the tutorial since I kept getting the error:

# command-line-arguments
./main.go:45:11: undefined: InitializeEvent

when following the tutorial since I ran it with go run main.go using go1.18.3. It's not obvious to me that we need to include wire_gen.go to make it work.

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[cglotr]

There's a typo in the title of commit message, please fix, s/to to/how to

@jayzhuang i have changed the commit msg

[jayzhuang]

LGTM

[jayzhuang]

+@stytchiz who have write access

[stytchiz]

Thanks @jayzhuang :)