Release sources

[Chris Johns]

Hi,

The last snapshot ....

 https://ftp.rtems.org/pub/rtems/releases/5/5.0.0/5.0.0-m2003/

has a release process bug. The bug is due to the way the sources are collected
and packaged. I end up with two copies of the top level sources, the top level
file and an almost identical copy in `sources`. The ones in sources are wrong
and the top level ones are correct. Having two copies is confusing.

If I remove the copy in `sources` and just have the top level ones you get an
error when building the kernel or libbsd as it first tries `sources`, fails then
tries the top level directory which works. It could be confusing to see an error.

I am proposing all sources are placed in `sources` and we have no top level
sources. I will update the README and documentation.

Only having sources in `sources` is a change from how RTEMS has been released in
the past so I feel this needs to be discussed and approved before I make any
changes.

Thanks
Chris