Jest: more cli options and cli options documentation

[kentor]

It would be nice if we could override testRegex in the cli instead of having to edit package.json. Also would be nice to have a doc page with available cli flags.

Loving jest 16 so far 👍 Using it as a drop in replacement for other people's projects that are using mocha, but jest's reporting and watching features are superior.

[tizmagik]

As a workaround, you could pass in a configuration file to the CLI:

jest --config ./jest.config.json

[maximderbin]

+1 for cli docs page

[cpojer]

We added some docs for the CLI options.

I think the workaround @tizmagik provided is reasonable. You can also specify a config as a string, like jest --config='{"testRegex": …}'.