Remove examplar workflow

[peterdesmet]

@mtrekels, the README currently includes a number of repetitions:

README	source
introduction	https://github.com/mtrekels/b3alien/blob/main/docs/introduction.rst
architecture	https://github.com/mtrekels/b3alien/blob/main/docs/architecture.rst
Exemplar workflow	https://github.com/mtrekels/b3alien/blob/main/docs/usage.rst

• Do you maintain these in two places or is the README generated somehow?
• Note that for architecture and examplar workflow, images are broken on pypi: https://pypi.org/project/b3alien/
• Can you remove the examplar workflow from the README? It creates a lot of repetition, including on the b3 website: https://docs.b-cubed.eu/software/b3alien/readme/#exemplar-workflow-to-determine-the-rate-of-establishment vs https://docs.b-cubed.eu/software/b3alien/usage/
• While you're add it, can you update https://github.com/mtrekels/b3alien/blob/main/docs/introduction.rst to have the correct URL (with https) for the b-cubed website?