README: Split the installation section : one document for each linux distribution

Signed-off-by: Jerome Flesch <jflesch@wyplay.com>
README/Doc: Fix links

Signed-off-by: Jerome Flesch <jflesch@wyplay.com>
Merge branch 'stable' into unstable

Conflicts:
	README.markdown

Signed-off-by: Jerome Flesch <jflesch@wyplay.com>