Following the steps of https://docs.softwareheritage.org/devel/tutorials/add-new-package.html
[x] Bootstrap repository in forge (https://forge.softwareheritage.org/source/swh-perfecthash/)
[x] Add to swh-environment
[x] Add to jenkins (337d62d - checked via B24255)
[x] [Add to docs](https://docs.softwareheritage.org/devel/swh-perfecthash/index.html)