[2.9] update example in known_hosts.py (#71418)

This addresses the issue reported in #71417

changelogs/fragments/71417-fix-non-existant-parameter-reference.yml

@@ -0,0 +1,2 @@
+minor_changes:    
+  - known_hosts - fix reference to non-existent parameter in example (https://github.com/ansible/ansible/issues/71417)

lib/ansible/modules/system/known_hosts.py

@@ -67,7 +67,7 @@ EXAMPLES = '''
 
 - name: Another way to call known_hosts
   known_hosts:
-    hostname: host1.example.com   # or 10.9.8.77
+    name: host1.example.com   # or 10.9.8.77
     key: host1.example.com,10.9.8.77 ssh-rsa ASDeararAIUHI324324  # some key gibberish
     path: /etc/ssh/ssh_known_hosts
     state: present