Updating some compose info for devs

slides/intro/Compose_For_Dev_Stacks.md

@@ -60,6 +60,10 @@ Before diving in, let's see a small example of Compose in action.
 If you are using the official training virtual machines, Compose has been
 pre-installed.
 
+If you are using Docker for Mac/Windows or the Toolbox, docker-compose comes with them.
+
+If you're on Linux desktop/server, you'll need to get the lastest at https://github.com/docker/compose/releases
+
 You can always check that it is installed by running:
 
 ```bash
@@ -137,21 +141,23 @@ services:
 
 ## Compose file versions
 
-Version 1 directly has the various containers (`www`, `redis`...) at the top level of the  file.
+Version 1 (or no version) is legacy and shouldn't be used.
 
 Version 2 has multiple sections:
 
-* `version` is mandatory and should be `"2"`.
+* `version` is mandatory and should be `"2"` or later.
 
-* `services` is mandatory and corresponds to the content of the version 1 format.
+* `services` is mandatory. A service is one or more replicas of the same image running as containers.
 
 * `networks` is optional and indicates to which networks containers should be connected.
-  <br/>(By default, containers will be connected on a private, per-app network.)
+  <br/>(By default, containers will be connected on a private, per-compose-file network.)
 
 * `volumes` is optional and can define volumes to be used and/or shared by the containers.
 
 Version 3 adds support for deployment options (scaling, rolling updates, etc.)
 
+Docker Docs has good info on versions https://docs.docker.com/compose/compose-file/
+
 ---
 
 ## Containers in `docker-compose.yml`
@@ -260,6 +266,8 @@ Removing trainingwheels_www_1 ... done
 Removing trainingwheels_redis_1 ... done
 ```
 
+Use `docker-compose down -v` to remove everything including volumes.
+
 ---
 
 ## Special handling of volumes