I'd use headings instead of a table.
```rst
`ARXIV_API_URL`
^^^^^^^^^^^^^^^
The URL of ArXiv query API. **Default:** `https://export.arxiv.org/api/query`

...
```
The table doesn't look that good (horizontal scrolling), its content has nothing to do with tabular data, and it will be a pain to maintain.
http://invenio.readthedocs.org/en/latest/ext/arxiv.html