Docs: Minor updates to PKI Secrets Engine (#6778)
Docs: Minor updates to PKI Secrets Engine (#6778)

* Docs: Minor updates to PKI Secrets Engine

- Update `ttl` and `max-lease-ttl` values from _43800_ which
  appears to be a typo, to _4380_; this helps avoid warnings
  like: "The expiration time for the signed certificate is
  after the CA's expiration time. If the new certificate is
  not treated as a root, validation paths with the
  certificate past the issuing CA's expiration time will
  fail." when following the Quick Start and using the tuned
  Root CA TTL of 8760h
- Change _my-role_ role name to _example-dot-com_ in **Setup**
  to help reduce confusion and match what is used in
  **Quick Start**

* ttl changes

hartsock/vault,rnaveiras/vault,rnaveiras/vault,kingland/vault,rnaveiras/vault,joelthompson/vault,hartsock/vault,hartsock/vault,quixoten/vault,joelthompson/vault,hashicorp/vault,joelthompson/vault,quixoten/vault,quixoten/vault,hashicorp/vault,kingland/vault,hartsock/vault,kingland/vault,kingland/vault,hashicorp/vault,joelthompson/vault,hashicorp/vault,rnaveiras/vault,hashicorp/vault,rnaveiras/vault,quixoten/vault,hartsock/vault,kingland/vault,hashicorp/vault