Detab flexbox yml files
Add missing line-box-contain
Small updates, missing props and rename of <ident>
Add skeleton Display yml files

Not added support info for `display` yet
Add skeleton images YML files

…no browser support included yet
Add skeleton Line grid YML files
Add Lists YML files
Fix column-gap copy and paste error
Add missing milticol YML files

…need to check for updated browser support
Add support info for display property