improve upon BU_Toolchains_Table

Signed-off-by: Fotis Georgatos <fotis@cern.ch>
remove all Basic Usage files

Signed-off-by: Fotis Georgatos <fotis@cern.ch>
bump minor, fix inst last section

Signed-off-by: Fotis Georgatos <fotis@cern.ch>
rewire legacy configuration paragraph, move it around

Signed-off-by: Fotis Georgatos <fotis@cern.ch>