Add ability to customize document head #270
Description
Is your feature request related to a problem? Please describe.
It is unfortunate when changes need to be made to the document head because
the only way to do that is to override the entire layout. This makes future primer-spec
improvements a maintenance issue because spec.html is no longer fetched from the
remote theme source.
Describe the solution you'd like
Add an included file to the end of the document head, so only the customizations
need to be stored and maintained within the repo having the theme applied.
Describe alternatives you've considered
The only alternatives are to fork and maintain a separate primer-spec, or host the
spec.html which will limit primer-spec authors' upgrades.