Documentation: fix lfs, stevedonovan and orbit broken links

[jlaurens]

This is not ready to merge.

Some links were broken and have been fixed in files of the repo.

I could not build the documentation by myself with ldoc (error: unknown file attribute: b)
and I could not find a way to make ldoc replace "lsf.dir" in file

docs_topics/04-paths.md

by

<a href="https://lunarmodules.github.io/luafilesystem/manual.html#dir">lfs.dir</a>

in file

docs/manual/04-paths.md.html

instead of

<a href="http://stevedonovan.github.io/lua-stdlibs/lfs.html#dir">lfs.dir</a>

which is the broken link

[Tieske]

@jlaurens I fixed the isues. And pushed the changes on your branch. I lost the attribution to you in the process.

Can you rebase and recommit to fix the attribution? then this is good to go I think.

[jlaurens]

rebased