Remove contributors list (too annoying to maintain), people can use Commits > Contributors (https://github.com/zsh-users/zsh-syntax-highlighting/contributors) to access the same list

GREETINGS.md

@@ -1,19 +0,0 @@
-Authors / Greetings
-===================
-
- * [Roy Zuo](https://github.com/roylez)
- * [Julien Nicoulaud](https://github.com/nicoulaj)
- * [Dave Ingram](https://github.com/dingram)
- * [Mounier Florian](https://github.com/paradoxxxzero)
- * [Jonathan Dahan](https://github.com/jedahan)
- * James Ahlborn
- * [Andreas Jaggi](https://github.com/x-way)
- * [Wayne Davison](https://github.com/WayneD)
- * [Suraj N. Kurapati](https://github.com/sunaku)
- * [Takeshi Banse](https://github.com/hchbaw)
- * [Sorin Ionescu](https://github.com/sorin-ionescu)
- * [Clayton Parker](https://github.com/claytron)
- * [Arlen Cuss](https://github.com/celtic)
- * [Nakamura Yoshitaka](https://github.com/nakamuray)
- * [Ted Naleid](https://github.com/tednaleid)
- * [garinger](https://github.com/garinger)