TOC: Rearrange APIs in order of popularity

[hhunter-ms]

Move Workflows up in the TOC since it's a popular API... ie:

Service invocation Pub/sub Workflows State management ...

Need to update:

• [x] Quickstart TOC
• [x] Building blocks TOC
• [x] API reference docs TOC
• [x] Component specs TOC
• [x] Diagrams that show the building blocks