@anon92994695 my login in this forum is @scelles (and my github login is scls19fr and I’m fine being part of this org… but only after creating a first repository named roadmap where we could define general goals of the org).
Similar to Issues · JuliaEditorSupport/roadmap · GitHub
(but please read the whole content of my post before considering adding me to JuliaMakers)
I must admit that I’m a bit skeptic about JuliaEmbedded
Not sure if we need an Hello World package 
It seems to me that it’s currently only a nearly empty Github org with one user and empty projects (at least currently and since August 2019).
I don’t see any “roadmap” in this Github org and the discussion about its creation is available at Bring Julia code to embedded hardware (ARM) - #32 by imcinerney
In this discussion I noticed that there’s also Julia-Embedded
So JuliaEmbedded (from @imcinerney) shouldn’t be confused with Julia-Embedded (@Amin_Yahyaabadi @terasakisatoshi ) 
My fear is that, without clear goals, JuliaMakers could end up like a set of Hello World packages also.
We probably need to find more other posts in this forum related to hardware hackers and count possible contributors (and possibly pinging them here to have a discussion) before going beyond.
About your specific question…
Now I have an administrative noob question. How do I add repos to an org?
you just can’t… an other repository owner can transfer ownership of a repository to a Github org not the opposite.
To be more precise if you are considering the opposite you can just fork a repository into an organization (but not transfer it).
Procedure for transferring repos is available at Transferring a repository - GitHub Docs
When you transfer a repository, its issues, pull requests, wiki, stars, and watchers are also transferred
But we should be aware that there is no value in transferring ownership of a repository to an org if there’s still only one developer (and maybe only one user… the developer himself) of this package.
To be able to create a kind of Julia Maker community you need to have a kind of “flagship project” and that’s an important goal to define.
Maybe people considering “making hardware” with Julia should first tackle the problem of being able to have a device able to quickly boot and run Julia (as I was asking in Running console Julia app with small hardware and small Linux OS but with fast boot)
What are examples of the lightest system able to run Julia (and that could be a good base for hardware making) ?
Can we be closer to metal that Raspbian on RPi while having Julia running?
What can be flagship project(s) which could be interesting to Julia community / makers community?