refactor(docs): restructure min requirements section

The ordering of the setup guide is quite confusing, primarly because the
min requirements section is overly verbose. Reconcile this information
into a single table, and present the most important information at the
start of the document i.e. how to get the source, and the tools to
compile.

Change-Id: I1c4d708259e152b101c7282dad19e467d6c36519
Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>
1 file changed