docs: drop code commentary readers haven't seen yet

The reader hasn't read main.ts at this point, so notes about the
import.meta.main guard and the test importing the handler directly are
detail without context. Trim to a one-line summary of what each file is
for.

Author: bartlomieju

runtime/getting_started/first_project.md

@@ -29,11 +29,8 @@ my_project
 ```
 
 [`deno.json`](/runtime/fundamentals/configuration/) holds your project
-configuration. `main.ts` contains a small HTTP server built on
-[`Deno.serve`](/api/deno/~/Deno.serve), showing off the built-in HTTP server,
-`Response.json()`, and TypeScript working out of the box. The handler is
-exported and guarded by `import.meta.main`, so `main_test.ts` can import and
-call it directly without binding to a port.
+configuration. `main.ts` is a small HTTP server built on
+[`Deno.serve`](/api/deno/~/Deno.serve), and `main_test.ts` has the tests for it.
 
 ## Run your project
 
@@ -46,7 +43,7 @@ cd my_project
 You can run this program with the following command:
 
 ```bash
-$ deno main.ts
+$ deno -N main.ts
 Listening on http://localhost:8000/
 ```