Use Vercel dir convention

Author: lukechilds

src/index.js renamed to api/index.js

@@ -2,9 +2,9 @@
  "name": "reverse-shell",
  "version": "1.1.3",
  "description": "Reverse Shell as a Service - https://reverse-shell.sh",
- "main": "src/index.js",
+ "main": "api/index.js",
  "files": [
- "src"
+ "api"
  ],
  "scripts": {
  "test": "xo && nyc ava",