Add a section with tech stack and style guides
requested to merge gitlab-community/gitlab:376_add_information_about_gitlab_tech_stack_in_doc into master
What does this MR do and why?
Add a section with the GitLab tech stack on the Contribute to GitLab development page https://docs.gitlab.com/ee/development/contributing/
MR acceptance checklist
Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.