Clarify that bbastov is the style of Hound CI 2.

Continued from https://github.com/gitlabhq/gitlabhq/pull/6786

Added Rubocop link.

Set option B, previous line.

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Since I wrote this, Hound docs improved. [They say their default is](https://github.com/thoughtbot/guides/tree/master/style#formatting):

> If you break up a chain of method invocations, keep each method invocation on its own line. Place the . at the end of each line, except the last.

I don't think bbastov specifies one method per line, so in theory Hound should check more like "Option B + one method per line."

In practice however hound [does not seem to enforce one method by line by default](https://github.com/cirosantilli/test/pull/9#discussion-diff-13595616R36), so it ends up being the same as bbastov because of that bug.

For now we can leave Option B.

For the future I propose we use one single tool and the style that comes with it to reduce the probability of conflicts between the styles, so either:

- Hound + [hound style](https://github.com/thoughtbot/guides/tree/master/style#ruby)
- Rubocop + [bbastov style](https://github.com/bbatsov/ruby-style-guide)