Add stacks-userguide.md

[freignat91]

Add "stacks-userguide.md" to docs

Summary:

• 1 Stack commands
• 2 Stack file description
• 3 ETCD storage
• 4 Networks
• 5 HAProxy

Test: read-it :)

[subfuzion]

Excellent!

[jhaynie]

curious why we're using publish_port and internal_port? why not use a more docker standard syntax internal_port:external_port such as:

myservice1:
   image: appcelerator/pinger:latest
   public:
       - name: myexternalname
         ports: 3000:3001

[jhaynie]

Protocol could be handled the same way as 3000:3001/udp

[subfuzion]

@jhaynie We did a lot of debating over it initially because in this case, publish_port is not for exposing the container port on a node host port. Instead, it takes the service port (used to access the service internally within the stack network) and publishes it via the reverse proxy, mapping it as desired, for external use. The debate was over using a format that was familiar vs. confusing people with the different intention since HOST:CONTAINER mapping already has a well-established in Docker. However, that argument did go out the window when we decided to use that format for amp service create anyway, so we definitely should revisit this. The format we use for amp service create, is more powerful; it even supports specifying a name, so for example: admin:3000 will map the service port to admin via haproxy.

[jhaynie]

ah ok that makes a lot of sense.