Add "Go To Source" for Docs?

[Jacob via Digitalmars-d]

Well a lot of the times I'm browsing the phobos library 
documentation I want to go to the source code, but there's no 
easy way to go there directly from the docs. Some modules have a 
link to the source file but I think that's done manually as many 
of them don't. I think it'd be beneficial to have a way to tell 
the doc generator to include a "go to source" button at each doc 
entry of function/type. With the option to set a github repo or 
other link as the destination of the link, it should also include 
the line number when outputting the docs. Might be a bit specific 
for github there though, as setting the line number just involves 
adding a number to the end of the link. Whereas being able to set 
a local file as a link might be desired as well. But I don't 
think you can tell the OS to open the file at a certain line with 
just a file uri.