Add section on supported content types and streaming options

[welteki]

Description

• Add section on supported content types and streaming options
  Add a section to the workload page to list the supported HTTP streaming
  options: SSE, Websockets and NDJSON.

• Add note on function auth to invocations page

Motivation and Context

• I have raised an issue to propose this change (required)

Document the supported content types for functions.

How Has This Been Tested?

Verified locally the docs render correctly.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I've read the CONTRIBUTION guide
• I have signed-off my commits with git commit -s