Tvars:
Two options:
1. Create and edit your HTML fragments in a normal Alfresco space, and
use a content rule to auto-promote to a Web Project (using the pre-built
action or creating your own custom action using the Javascript API)
2. Create a very simple web form that has one defined element,
a rich-text field (using whatever appearance annotation you want
to customize what functions and plug-ins you want to enable). You
can associate that form with a simple Freemarker template to strip
out the HTML from the generated XML and write as a standalone
HTML fragment. Your end-users would then be able to click edit
on that HTML fragment and re-load upu the form for editing.
The goal of our authoring services is to make content re-usable,
repurposable, and well-structured. Obviously, you don't always
need that. In the simple case, just use a very simple form. Starting
with this model, though, means that you can extend over time to
increasingly structured data entry (extend your XSD to start capturing
titles and abstracts) or content reuse (associate more templates to
generate increasingly different output).
A separate feature enhancement to simply load up the WYSIWYG editor for an HTML fragment without an associated template is noted. However, to get started today, I'd recommend either one of the two above. Ultimately, if we were to address the feature improvements, under the covers we'd likely make the out of the box use of the WYSIWYG editor works exactly as noted in #2 above.
Cheers. Hope that helps.
Kevin