cherry-pick from master: I615602a3d8f9970e36399b98dadb5e2f03638444

docs: various stylesheet changes
indent tables
revise figure class
add caption classes for tables and images
add styles for xml reference docs (used by resource types docs)
tweak styles for the icon tables to eliminate obscure 'caption' class

Change-Id: I23f53d884f39a5f6a4b45172186e0d1c7619da30