Add diagram to demo

[krlmlr]

and/or "Getting started".

Ensure Twitter card works.

[krlmlr]

The diagram should document the workflow and the various commands available in fledge. Should we use mermaid?

[krlmlr]

I have a diagram that we could use or adapt:

FledgeFlow.zip

[maelle]

just noting that when there is a diagram it could be used as social media image for the repo too. https://github.blog/2019-04-17-custom-open-graph-images-for-repositories/

[krlmlr]

Not needed for a quiet release.

[maelle]

Diagrams for the different release fates would be nice.

[maelle]

with birds

[maelle]

If only I could draw. conventional commits bird would wear glasses. bullets commits bird would look more relaxed (but in the end, conventional commits bird would have less work so it's a bit of a https://en.wikipedia.org/wiki/The_Ant_and_the_Grasshopper situation)