Update theme submodule

Signed-off-by: Alan Orth <alan.orth@gmail.com>
Update theme submodule

Signed-off-by: Alan Orth <alan.orth@gmail.com>
Add RELATIVE_URLS config, use when testing locally
Update theme submodule

Signed-off-by: Alan Orth <alan.orth@gmail.com>
Update README
Add GNU link