Fix a minor indentation problem

Author: morinokami

00-introduction/solution.ts

@@ -5,7 +5,7 @@ import { Equal, Expect } from "../helpers";
 /**
  * 0. Warmup, try assigning "World" to `type Hello`.
  */
- namespace zero {
+namespace zero {
   type Hello = "World";
 
   type test1 = Expect<Equal<Hello, "World">>;