because the files generated by jsdoc were output to `docs/_site`, they were not processed as liquid templates, which meant the custom reporter tutorial was broken.

to fix this, we needed to:

1. change the output directory of jsdoc to `docs/api` (just somewhere else)
2. add this to `.gitignore`, obviously
3. tell eleventy to _ignore_ `.gitignore` (just rely on its `.eleventyignore` file)
4. tell eleventy to pass-through all assets underneath `docs/api` (css, images, etc)
5. update the file-loading 11ty data script to output a raw file
6. update the tutorial to use a fenced code block (jsdoc markdown plugin seems to strip html?) and tell Prettier to ignore the liquid template directive

also:

- removed link to google group
- prettier-related reformats
- tweak data script to use `fs.promises`

Signed-off-by: Christopher Hiller <boneskull@boneskull.com>