Release 0.8.4

What's Changed

• Adding reference to Gilbert Skill Score & Equitable Threat Score docstrings by @Steph-Chong in #420
• Update download links for data fetching by @tennlee in #434
• (one of five) Add mathjax and improved docstrings to several scores by @tennlee in #441
• Adds fraction correct (as alternative term to accuracy) to API and updates included.md table by @Steph-Chong in #437
• Renaming explanation to tutorial gallery by @Steph-Chong in #451
• Contributing Guide: adds (a) reference to providing feedback, (b) code of conduct section by @Steph-Chong in https://github.com/nci/scores* Minor release 0.8.4 by @tennlee in #452

Full Changelog: 0.8.3...0.8.4