Merge branch '51-add-what-is-fusiondirectory-prerequisite-certified-distribution' into '1.3'

Resolve "add what is fusiondirectory / prerequisite /certified distribution"

Closes #51

See merge request fusiondirectory/dev-manual!83

(cherry picked from commit c63507a4)

2b4c2c93  feat(doc) add what is fusiondirectory / prerequisite /certified distribution