readme: Add Intel information

Add some information about the new available Intel driver and adjust
formatting of the code examples.

Signed-off-by: Antonio Caggiano <antonio.caggiano@collabora.com>
3 jobs for intel-perfcnt in 2 minutes and 26 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Check
passed #5820294
clang-format

00:00:33

 
  Build
passed #5820296
aarch64
aarch64

00:01:52

passed #5820295
kvm
x86_64

00:00:44