Code blocks should not be spaced 4 times, as this will
prevent the code from being colored. They should
also be spaced the same as the lists they are a part
of, to make reading easier.

- Breaks up into more sections.
- Also minor fixes to pages within sections.

- Also makes other minor Markdown fixes that were near the main fixes.

bundler gem has been included in the Docker official Ruby image since 2.1.
Signed-off-by: NTakuya Noguchi <takninnovationresearch@gmail.com>

Also, move the old linting docs to the new location.