There is no documentation for this. We did a developer beta for HTML a couple months ago. The current implementation is/will be undergoing an overhaul based on our internal and beta feedback. I don’t have an ETA on when HTML-based development will be supported at this time; and while I’d be trying these things out myself were I in your shoes, I’d be remiss if I didn’t at least mention that current implementations will not be backwards compatible with likely upcoming changes prior to this being supported.
I don’t want to discourage developers pushing the envelope with these capabilities, but want to err on the side of transparency/appropriate expectations WRT to support/maintainability of htmlTile.
tl;dr - use at your own risk and the current implementation can and will change without notice.