Since you don't assume familiarity with GH pages elsewhere, maybe something like
"""
In your explainer, point readers to the index.html generated from spec.emu via markdown like
You can browse the [ecmarkup output](https://ACCOUNT.github.io/PROJECT/)
or browse the [source](https://github.com/ACCOUNT/PROJECT/blob/master/spec.emu).
where ACCOUNT and PROJECT are the first two path elements in your project's Github URL.
For example, for github.com/tc39/template-for-proposals, ACCOUNT is tc39 and PROJECT is template-for-proposals.
Since you don't assume familiarity with GH pages elsewhere, maybe something like
"""
In your explainer, point readers to the
index.html
generated fromspec.emu
via markdown likewhere ACCOUNT and PROJECT are the first two path elements in your project's Github URL. For example, for
github.com/tc39/template-for-proposals
, ACCOUNT istc39
and PROJECT istemplate-for-proposals
."""