docs(www): Update making-components-discoverable.md / Expand (#15393)
docs(www): Update making-components-discoverable.md / Expand (#15393)

* Update making-components-discoverable.md / Expand

Expanded the stub and added a more elaborate (yet short) description on the advantages of discoverability for reusing modular components, added bit's shared component hub, elaborated on storybook and added styleguidist for component discoverability.

* chore: format

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