Add Analyzer development guide to navigation

Add navigation item to global navigation

• Link to the merge request that introduced the new page: Unknown
• Give the MR a descriptive title.
• Optional. Link to the review app showing the new page: https://russell-nav-add-analyzer-dev-guide.docs.gitlab-review.app/ee/development/sec/analyzer_development_guide.html

Target page: https://docs.gitlab.com/ee/development/sec/analyzer_development_guide.html#analyzers-development