Update contribution-guidelines/CONTRIBUTING.md, contribution-guidelines/docs/developer/README.md, contribution-guidelines/docs/team-access-plugin.md, contribution-guidelines/docs/team-statistics-plugin.md, contribution-guidelines/docs/developer/mattermost-local/mattermost/config/config.json.sample, contribution-guidelines/docs/welcomebot-plugin.md, contribution-guidelines/docs/developer/general-developer-guideline.md, README.md files