DOC: Remove errant backslashes from the Ecosystem tab on new website.
Pandas Sprint at PyData NYC :-)
Fixed at the direction of @datapythonista 

The only file touched is a markdown file.

- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `black pandas`
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry
