Add Gendex Generator module details

[Joppla]

Added Gendex Generator module information to modules.md.

[BertKoor]

Could you please add the data of the German chancellors & presidents module again?
That one is not yours, so why is that data deleted?
See https://github.com/webtrees/webtrees.github.io/pull/211/changes

[Joppla]

@BertKoor: That was not my intention. How to make it correct? I have tried something, but I m not sure if it is now correct done, it seems correct, but is it in the pull request?

[fisharebest]

@BertKoor - it looks OK to me now. Have I missed something? Can you check before I merge.

[BertKoor]

Looks fine to me now.
Thx!

[BertKoor]

I've looked again, wondering why this was not merged yet, and something's bothering me.

When inspecting all commits in isolation, then it's fine. But when inspecting the net result, then a paragraph for deprecated module "Gov4Webtrees - by ric2016" for webtrees 1.7 is added.

@Joppla: my advise is to delete your fork of webtrees.github.io (that should also cancel this PR) and do the addition with the web interface: edit this page instead.