I just committed a new version of the FPDoc Manager :-)
Now support for additional description directories are disabled by
default, this option deserves more support for efficient use. Please
report your suggestions if you find such a feature useful, and what
support you expect.
Instead I added a LazDE form for editing descriptions, by an dblclick on
a unit name. It was a bit tricky to make the LazDE main form usable for
this purpose, could some support be added to LazDE for such use?