Add content to TypeScript roadmap

src/roadmaps/typescript/content/101-typescript-types/115-type-assertions/100-as-const.md

@@ -4,7 +4,7 @@
 
 For example:
 
-    ```
+```typescript
 const colors = ['red', 'green', 'blue'] as const;
 
 // colors is now of type readonly ['red', 'green', 'blue']

src/roadmaps/typescript/content/101-typescript-types/115-type-assertions/101-as-type.md

@@ -4,7 +4,7 @@ as is a type assertion in TypeScript that allows you to tell the compiler to tre
 
 For example:
 
-    ```
+```typescript
 let num = 42;
 let str = num as string; 
 

src/roadmaps/typescript/content/101-typescript-types/115-type-assertions/102-as-any.md

@@ -4,7 +4,7 @@
 
 For example:
 
-    ```
+```typescript
 let anyValue: any = 42;
 
 // we can assign any value to anyValue, regardless of its type

src/roadmaps/typescript/content/101-typescript-types/115-type-assertions/103-non-null-assertion.md

@@ -2,9 +2,7 @@
 
 The non-null assertion operator (!) is a type assertion in TypeScript that allows you to tell the compiler that a value will never be null or undefined.
 
-For example:
-
-    ```
+```typescript
 let name: string | null = null;
 
 // we use the non-null assertion operator to tell the compiler that name will never be null