Document lint rule set configuration.

[pq]

From @pq on October 13, 2015 15:33

Lint rules can be enabled via .analysis_options and the syntax needs to be documented.

linter:
  rules:
    - camel_case_types
    - empty_constructor_bodies
    - library_names
    - super_goes_last

Copied from original issue: dart-lang/analyzer_cli#70

[pq]

From @zoechi on October 13, 2015 19:22

And the list of lint rule names. Looks like #69 is about this, right?

[bwilkerson]

@pq Is this still needed?

[zoechi]

https://www.dartlang.org/guides/language/analysis-options should do it
The linter packages readme also contains this link