Support for multiple charts with headings

[andersennl]

It would be useful to be able to render multiple charts, separated by blank lines, each with its own heading.

Example:

_Scenario 1
Service 1
 connection: (3)
Service 2
 connection: (2)

_Scenario 2
Service 1
 connection: (10)
Service3
 connection: (8)

[rob-gordon]

@andersennl Moved this over to a discussion so that other people can express interests and suggest syntax. Thanks for your suggestion!

[andersennl]

The syntax in my example was just picked totally random.