docs: Add more hints to not use the internal toolchain.

The internal toolchain is deprecated and no longer maintained, To make it
clearer that pbs-stage1 on is now the preferred solution add a note to the
toolchain step.

Change-Id: I476946ab74591cc447fcd7f0d17edab1868bedb4
Signed-off-by: Soeren Grunewald <soeren.grunewald@avionic-design.de>
Reviewed-on: http://review.adnet.avionic-design.de/246
Reviewed-by: Hendrik Lippek <hendrik.lippek@avionic-design.de>
docs: Update documentation to match github layout.

The documentation does still refer to old repositories we no longer maintain.

Change-Id: I1911e05ec50aeadbd9d6b5de884cc7ceb9f01199
Signed-off-by: Soeren Grunewald <soeren.grunewald@avionic-design.de>
Reviewed-on: http://review.adnet.avionic-design.de/245
Reviewed-by: Hendrik Lippek <hendrik.lippek@avionic-design.de>
docu: Use markdown for readme.

Convert our existing readme file into a version using markdown syntax.

Change-Id: I4db12bef31386af0b3e2a43a58b4900eb6aa7e03
Signed-off-by: Soeren Grunewald <soeren.grunewald@avionic-design.de>
Reviewed-on: http://review.adnet.avionic-design.de/275
Reviewed-by: Hendrik Lippek <hendrik.lippek@avionic-design.de>