Removed Docker production warnings

* Removed warnings.
* Removed inconsistent Community installation sections.
* Fixed all installation page descriptions.
* Removed old .inc files.

Docker-DCO-1.1-Signed-off-by: James Turnbull <james@lovedthanlost.net> (github: jamtur01)
Merge pull request #6053 from jamtur01/produpdate

Removed Docker production warnings
Replace 'private' with 'self-hosted' in a couple of places

Docker-DCO-1.1-Signed-off-by: Jérôme Petazzoni <jerome@docker.com> (github: jpetazzo)
Return devmapper errors with additional text
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Merge pull request #6069 from crosbymichael/dm-errors

Return devmapper errors with additional text
Merge pull request #6068 from jpetazzo/update-wording-private-self-hosted-registries

Replace 'private' with 'self-hosted' in a couple of places