* master:
Fix version
Improve the consistency of commit titles, branch names, tag names, issue/MR titles, on their respective project pages
Update CHANGELOG [ci skip]
Add some cosmetic changes to variables API documentation [ci skip]
Modify builds API documentation style [ci skip]
Modify :ci_variable factory
Add 'Build' prefix to Variables entry name in API docs index
Fix some typos
Add some fixes after review
Remove blank line
Update ./doc/api
Change :variable_id to :key as resource ID in API
Fix a typo in method description
Add create feature to variables API
Add missing 'not_found' checks in variables API
Add delete feature to variables API
Add update feature for variables API
Add features for list and show details of variables in API
Conflicts:
doc/api/README.md
lib/api/entities.rb
