[#293] Add documentation comments and tests for TS Definitions

Notable changes:
- Move index.d.ts from types/ to project root (needed for
  tsd-check module).
- Rename test.ts to index.test-d.ts and place it under root
  (needed for tsd-check module).
- Add tsd-check module to test Typescript Definitions.

Future Work:
The properties inverse, hidden, strikethrough and visible
of Chalk interface in index.d.ts needs to be documented.

types/tsconfig.json

@@ -1,9 +0,0 @@
-{
-	"compilerOptions": {
-		"module": "commonjs",
-		"target": "es6",
-		"noImplicitAny": true,
-		"noEmit": true,
-		"allowJs": true
-	}
-}