Fixed Vault return value usage from `data` to `vault.data`.

A test was failing due to use of old ipavault module return structure
and some places on the documentation were alse referring to it. All
ocurrences were fixed.

README-vault.md

@@ -197,7 +197,7 @@ Example playbook to make sure vault is absent:
       state: absent
     register: result
   - debug:
-      msg: "{{ result.data }}"
+      msg: "{{ result.vault.data }}"
 ```
 
 Variables

plugins/modules/ipavault.py

@@ -243,7 +243,7 @@ EXAMPLES = """
     state: retrieved
   register: result
 - debug:
-    msg: "{{ result.data }}"
+    msg: "{{ result.vault.data }}"
 
 # Change password of a symmetric vault
 - ipavault:

tests/vault/test_vault_symmetric.yml

@@ -203,7 +203,7 @@
       password: SomeNEWpassword
       state: retrieved
     register: result
-    failed_when: result.data != 'Hello World.' or result.changed
+    failed_when: result.vault.data != 'Hello World.' or result.changed
 
   - name: Retrieve data from symmetric vault, with old password.
     ipavault: