Mute expected errors in the examples

[ryyppy]

Not sure if this is wanted behavior, but some examples provoke an error, which might be confusing if you look at the examples... so in our flow-guide we added this configuration to the .flowconfig:

[options]
suppress_comment= \\(.\\|\n\\)*\\$FlowExpectedError

Maybe you also want to add this...
If this was left out intentionally, you can close this issue right away ;-)

[ptmt]

You're right, but since we can't use .flowconfig we need to adopt it in a different way. Let's see how many this kind of errors we will have.