Graham Land 431cc5f9a6 Docs: Add Auto Unseal Rekey example (#5952)
* Add KMS Rekey example

I've had customers looking for AWS KMS rekeying examples today - when using pgp keys.
This example would have clarified what they needed to do.

* Replaced KMS reference with Auto Unseal

``` bash
Rekey an Auto Unseal vault and encrypt the resulting recovery keys with PGP:
```
2019-01-03 09:23:43 -05:00
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