Merge pull request #14096 from ulyssessouza/migration

Add migration V1 -> V2 info

compose/cli-command-compatibility.md

@@ -6,7 +6,8 @@ title: Compose command compatibility with docker-compose
 
 The `compose` command in the Docker CLI supports most of the `docker-compose` commands and flags. It is expected to be a drop-in replacement for `docker-compose`. 
 
-If you see any Compose functionality that is not available in the `compose` command, create an issue in the [Compose](https://github.com/docker/compose/issues){:target="_blank" rel="noopener" class="_"} GitHub repository so we can prioritize it.
+If you see any Compose functionality that is not available in the `compose` command, create an issue in the [Compose](https://github.com/docker/compose/issues){:target="_blank" rel="noopener" 
+class="_"} GitHub repository, so we can prioritize it.
 
 ## Commands or flags not yet implemented
 
@@ -26,4 +27,39 @@ either because they are already deprecated in `docker-compose`, or because they
 
 Global flags:
 
-* `compose --compatibility` Deprecated in docker-compose.
+* `--compatibility` has been resignified Docker Compose V2. This now means that in the command running V2 will behave as V1 used to do.
+  * One difference is in the word separator on container names. V1 used to use `_` as separator while V2 uses `-` to keep the names more hostname friendly. So when using `--compatibility` Docker 
+    Compose should use `_` again. Just make sure to stick to one of them otherwise Docker Compose will not be able to recognize the container as an instance of the service.
+
+## Config command
+
+The config command is intented to show the configuration used by Docker Commpose to run the actual project.
+As we know, at some parts of the Compose file have a short and a long format. For example, the `ports` entry.
+In the example below we can see the config command expanding the `ports` section:
+
+docker-compose.yml:
+```
+services:
+  web:
+    image: nginx
+    ports:
+      - 80:80
+```
+With `$ docker compose config` the output turns into:
+```
+services:
+  web:
+    image: nginx
+    networks:
+      default: null
+    ports:
+    - mode: ingress
+      target: 80
+      published: 80
+      protocol: tcp
+networks:
+  default:
+    name: workspace_default
+```
+
+The result above is a full size configuration of what will be used in by Docker Compose to run the project.