Add docs: Portal quickstart

[joeyaiello]

We should have a quickstart doc outlining how to do the following from the Azure portal:

• create a function app
• create a function
  • timer trigger
  • HTTP trigger
• add a module dependency
• pack/publish to Azure
• show it working

[TylerLeonhardt]

Today, you can't create a function in the Portal. You only have the ability to publish a local function so for now, the docs for this are:

• create a function app in the portal
• push a local function app
• edit and run that function app in Azure

[TylerLeonhardt]

I think we can call this closed, right @joeyaiello?

[joeyaiello]

Let's leave this open as an updated version of this for our preview release. Might just be a validate pass, but this should be gone over before we ship publicly.

[asavaritayal]

/cc @ggailey777 as FYI

[anirudhgarg]

This is done.