Update wrapping.rst - example for unauthenticated unwrap (#789)

* Update wrapping.rst

Provide example of using unwrap with just the wrapping token. Previous example is non-functional unless already authenticated.

* update example

* correct automethod name

* doctest fixes

---------

Co-authored-by: Brian Scholer <1260690+briantist@users.noreply.github.com>

docs/usage/system_backend/wrapping.rst

@@ -8,10 +8,8 @@ Wrapping
 
 Unwrap
 ------
-Is Sealed
----------
 
-.. automethod:: hvac.api.system_backend.Seal.is_sealed
+.. automethod:: hvac.api.system_backend.Wrapping.unwrap
    :noindex:
 
 Examples
@@ -49,6 +47,34 @@ Example output:
     Unwrapped approle role token secret id accessor: "..."
 
 
+.. testcode:: sys_wrapping
+
+    import hvac
+
+    client = hvac.Client(url='https://127.0.0.1:8200')
+    client.write(
+        path="auth/approle-test/role/testrole",
+    )
+    result = client.write(
+        path='auth/approle-test/role/testrole/secret-id',
+        wrap_ttl="10s",
+    )
+    result_token = result['wrap_info']['token']
+
+    unwrapping_client = hvac.Client(url='https://127.0.0.1:8200', token=result_token)
+
+    # Do not pass the token to unwrap when authenticating with the wrapping token
+    unwrap_response = unwrapping_client.sys.unwrap()
+
+    print('Unwrapped approle role token secret id accessor: "%s"' % unwrap_response['data']['secret_id_accessor'])
+
+Example output:
+
+.. testoutput:: sys_wrapping
+
+    Unwrapped approle role token secret id accessor: "..."
+
+
 .. testcleanup:: sys_wrapping
 
     client.sys.disable_auth_method(