Add title and accDescription to chart examples

[lindseywild]

Is your feature request related to a problem? Please describe.
In order to help make the charts more accessible, it'd be great if we could include the newly added title and description to the examples (i.e. https://github.com/mermaid-js/mermaid/blob/develop/docs/pie.md)

Describe the solution you'd like
In the examples, ensure that title and accDescription exist in the example code.

Additional context
This is dependent on #2732 and which chart types have implemented the new fields. I think it should wait until that issue is complete before doing this.