dd1fe4296 gitlab-ci: Add MkDocs documentation support
fda3abf7c docs: Add platform-specific documentation
d88dc094e docs: Initialize MkDocs documentation structure
cc780e913 docs: Rename cross-building.txt to .md
243672823 docs: Create symlinks for NEWS/MAINTAINERS/CONTRIB
b9f507b82 docs: Set up MkDocs for IGT documentation site