Content updates

[im-samz]

Three streams of work:

1. Revised some of the terminology to match our marketing copy
2. Explicitly called out features we use which are being discussed at Ignite
3. Call to action at the end to visit our serverless booth.

Each commit relates to one section of the lab.

Regarding marketing copy:

• Full service name: Microsoft Azure Functions (usually just leave off the Microsoft)
• Service name after first mention: Functions
• Name of an instance of the service: function app
• Name of the functions deployed to the app: function(s)
  (I believe Durable is prefixed before each term)

[ikhemissi]

LGTM
This looks great, thanks a lot @im-samz !