Create a demo about how to compute locally a SWHID

Hi Morane,

in addition of this section of the devel documentation : https://docs.softwareheritage.org/devel/swh-model/persistent-identifiers.html?highlight=shwid#computing https://docs.softwareheritage.org/devel/swh-model/cli.html#command-line-interface

we talked about creating a video on how to locally compute a SWHID. Thanks by advance for your help!

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Migrated from T4543 (view on Phabricator)