Update validate_argument_spec.py (#80547)

##### SUMMARY
Fix example with file lookup, filter 'from_yaml' is required.


##### ISSUE TYPE
- Docs Pull Request

+label: docsite_pr

lib/ansible/modules/validate_argument_spec.py

@@ -69,7 +69,7 @@ EXAMPLES = r'''
 
 - name: verify vars needed for this task file are present when included, with spec from a spec file
   ansible.builtin.validate_argument_spec:
-        argument_spec: "{{lookup('ansible.builtin.file', 'myargspec.yml')['specname']['options']}}"
+        argument_spec: "{{(lookup('ansible.builtin.file', 'myargspec.yml') | from_yaml )['specname']['options']}}"
 
 
 - name: verify vars needed for next include and not from inside it, also with params i'll only define there