Review the developper manual and adapt it to the change we have made during filters / management reorganization

hello,

we have done lots of move during filters / management reorganization we need to check if the development manual is still current

https://gitlab.fusiondirectory.org/groups/fusiondirectory/-/issues?scope=all&utf8=%E2%9C%93&state=opened&label_name%5B%5D=filters