Add documentation surrounding --compatibility option in regards to deploy and resource and continued support for version 2 for non stack deployments

[jonl-percsolutions-com]

File: compose/compose-file/index.md
File: compose/reference/overview.md

Per pull request docker/compose#5684 and issue docker/compose#4513 there is now a --compatibility flag for using v3 deploy options when deploying via docker compose that converts the options to v2 format. There is no documentation yet on the --compatibility flag in the CLI reference and the compose-file documentation leads to the confusing, overly heated and long 4513 issue that takes forever to read and figure out about the compatibility flag. Please update the documentation to reflect these discussions to clarify that 2.x should be used for non swarm/stack deployments or --compatibility flag.

[docker-robott]

There hasn't been any activity on this issue for a long time.
If the problem is still relevant, mark the issue as fresh with a /remove-lifecycle stale comment.
If not, this issue will be closed in 14 days. This helps our maintainers focus on the active issues.

Prevent issues from auto-closing with a /lifecycle frozen comment.

/lifecycle stale

[docker-robott]

Closed issues are locked after 30 days of inactivity.
This helps our team focus on active issues.

If you have found a problem that seems similar to this, please open a new issue.

/lifecycle locked