Add newlines styleguide for Ruby code

cc @rymai @ayufan @zj

cc @grzesiek please enable some rubocop rules that can enforce such rules

mentioned in issue #20572 (moved)

Merge requests that enables some additional new line cops: https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/5637

Unfortunately static analysis is not so clever to say what can be grouped together to make logically coherent groups, and what can not. !5637 (merged) solves only the part of this issue but we would still need a clever custom cop to keep track on empty liner around internal blocks. Since Rubocop is not able to cover everything we should certainly have styleguide like this

We should syntax highlight these blocks as ruby.

Do we have a pattern of showing "Bad" before "Good"?

Reassigned to @dzaporozhets

This link won't actually work, will it?

@rspeicher it should. Same like scss-styleguide and doc-styleguide links below

@dzaporozhets I think these links work because they're defined at the bottom of the file?:

[doc-styleguide]: doc/development/doc_styleguide.md "Documentation styleguide"
[scss-styleguide]: doc/development/scss_styleguide.md "SCSS styleguide"

We're being rhetorical. This link will not work:

@rspeicher Aha yes, an image is worth a thousand words...

@rymai @rspeicher thanks. I did not know it defined below

Added 1 commit:

• f037f7a9 - Reorganize newlines guide to follow consistencty with other guides [ci skip]

@rspeicher updated to match style of other guides

Reassigned to @rspeicher

Added 1 commit:

• 94df7186 - Fix newline styleguide link for CONTRIBUTING.md

Added 1 commit:

• 13cabe71 - Add newlines styleguide for Ruby code

@rspeicher link added, commits squashed

mentioned in merge request !5692 (merged)

Status changed to merged

mentioned in commit fa95d9e4

mentioned in merge request !6213 (merged)

mentioned in issue gitlab#5678