[Dev] Adds .devcontainer manifest to help promote contributions (#342)

* Added a devcontainer file

* linting

* Added link to README

tooling/.prettierignore

@@ -1 +0,0 @@
-../assets/vendor/

tooling/.prettierrc.js

@@ -1,13 +0,0 @@
-module.exports = {
-  printWidth: 100,
-  tabWidth: 2,
-  useTabs: false,
-  semi: false,
-  singleQuote: true,
-  jsxSingleQuote: false,
-  trailingComma: 'none',
-  bracketSpacing: true,
-  arrowParens: 'always',
-  requirePragma: false,
-  endOfLine: 'lf'
-}