(I need it working for any forks)
So it looks like the only way it's to provide a link to some file in the root:
the [Root](/README.md)
or
the [Root](../README.md)
(if it's located at /doc/README.md for instance)
At the same time I can refer to any folder without referring to a file
the [Doc](/doc)
But if I try to put a link to the root folder:
the [real root](/)
the [real root](../)
I'll have a link such
https://github.com/UserName/RepoName/blob/master
which unlike the
https://github.com/UserName/RepoName/blob/master/doc
refers to 404
So if I don't want to refer to README.md in the root (I could havn't it at all)
After some research I've found this solution:
[the real relative root of any fork](/../../)
It always points to the default branch. For me it's Ok, so it's up to you
PS
With such a trick you can also access the following abilities:
[test](/../../tree/test)
- link to another branch
[doc/readme.md](/../../edit/master/doc/readme.md)
- open in editor
[doc/readme.md](/../../delete/master/doc/readme.md)
- ask to delete file
[doc/readme.md](/../../commits/master/doc/readme.md)
- history
[doc/readme.md](/../../blame/master/doc/readme.md)
- blame mode
[doc/readme.md](/../../raw/master/doc/readme.md)
- raw mode (will redirect)
[doc/](/../../new/master/doc/)
- ask to create new file
[doc/](/../../upload/master/doc/)
- ask to upload file
[find](/../../find/test)
- find file