deprecate lightMode config and update website and docs accordingly

[thescientist13]

Related Issue

resolves #52

Summary of Changes

1. Refactor website to use innerHTML
2. Update compiler to drop support for lightMode configuration and remove from build.js
3. Update documentation to remove reference to lightMode

TODO

1. Not sure if this implicates this getInnerHTML issue at all?
2. Open up a discussion to capture the original intent / use case, just for posterity in case its something worth re-investigating - just included with verify / ensure proper serialization of shadow roots excluding closed shadow roots from getInnerHTML #16