v9.3.0

Added

• Docs for primer-layout (grid), primer-support, primer-utilities, and primer-marketing-utilities
• Primer keys for category and module_type to package.json (for use in documentation and gathering stats)

Changes

• Removes docs from gitignore
• Removes the ^ from all dependencies so that we can publish exact versions
• Consolidates release notes from various sources into one changelog located in /modules/primer-css/CHANGELOG.md