This PR covers two sets of changes:
- Documenting the new `destination_peer` for proxy upstream definitions.
- Updating the exported-services config entry documentation.
Updates to the `exported-services` config entry include:
- As of 1.13.0 it is no longer only for Consul Enterprise
- A `PeerName` is now a possible consumer for an exported service.
- Added examples for OSS and Enterprise
- Linked to peering docs
Remove empty CodeBlockConfig elements. These elements are not
providing any benefit for the enclosed code blocks. This PR removes
the elements so so that the source is easier to read.