optionExamples: Allow to pass JSON instead of a string

[andy-hanson]

Current (taken from arrowReturnShorthandRule.ts):

optionExamples: [
    `[true]`,
    `[true, "${OPTION_MULTILINE}"]`,
],

Desired:

optionExamples: [
    true,
    [true, OPTION_MULTILINE],
],

We can just stringify the examples. This makes it easier to read (for the tslint contributor, in the documentation it will be the same), and the compiler will catch typos.

[andy-hanson]

This can be closed now.