Add LetsEncrypt to SkyCrypt README.md and updated Nginx Description

[WarpWing]

Added LetsEncrypt as an optional deployment tool in the documentation. This also helps service workers who only operate on secure origins—also updated the Nginx blurb to provide clarity on its benefits. Note that both are not optional to self-host SkyCrypt. Both LetsEncrypt and Nginx are suggestions for Production/Full Deployments and are not required for Hobby/Development Deployments.

[dukio]

why the ? after the Hypixel API key?

also... what's up with the capitalized casing :s

[WarpWing]

Weird spelling errors, should be all good now.