docs: fix broken animated flowchart

[aloisklink]

:bookmark_tabs: Summary

It looks like one of the recent Mermaid updates changed how the Mermaid flowcharts use CSS, so stroke-dasharray: 0; doesn't work anymore.

It's not too big of a deal, we can use -.-> dashed arrows instead, since they are already dashed.

Resolves #473

:straight_ruler: Design Decisions

N/A

:clipboard: Tasks

Make sure you

• [x] :book: have read the contribution guidelines
• [x] :computer: have added unit/e2e tests (if appropriate)
  • I believe Percy might have caught it, but since the issue was so minor, we just skimmed over it.
• [x] :bookmark: targeted master branch
• [x] ~Give @tstarbow-sfdc a chance to respond, in case they want a Co-authored-by credit~ Co-author credit given in https://github.com/mermaid-js/mermaid-cli/pull/481/commits/6a9e9f63788c73d06be8b851fc38f87a9513c6d1

[aloisklink]

@tstarbow-sfdc, I adapted your example from https://github.com/mermaid-js/mermaid-cli/issues/473#issuecomment-1407504177 to make this fix.

Do you mind if I credit you as a co-author by sticking a Co-authored-by: @tstarbow-sfdc <26944190+tstarbow-sfdc@users.noreply.github.com> in my commit (feel free to let me know if you'd prefer a different name/email).

[tstarbow-sfdc]

Glad I was able to help :) Happy to be co-author, or not. Either is fine with me.

[MindaugasLaganeckas]

Thank you both for a fine PR 😄