Remove period from subsection

www/docs/spawn.mdx

@@ -162,7 +162,7 @@ main(function *() {
 });
 ```
 
-### Spawning in a Scope.
+### Spawning in a Scope
 
 The `spawn()` operation always runs its operation as a child of the current
 operation. Sometimes however, you might want to run an operation as a child of a