cutting a real version
feat(#2): allows use of markdown external files
The README.md was updated with instructions on how to use the plugin
with external files or with markdown embedded in the html file.

Some demos were also created to depict the new usage possibilities.

Compatibility with the original format should remain the same - that
is, using markdown to render the **content of the slides**.
Merge branch 'external-file' of https://github.com/fegemo/bespoke-markdown into fegemo-external-file

Conflicts:
	package.json
Merge branch 'fegemo-external-file'