doc: xed from pin

Added a sentence saying where to find the XED include and lib directories in
a PIN distribution.

Change-Id: I1fc5de20d5ac2a5db9503e83a9e5dc40f7402931
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
doc: fix missing @ escape

Change-Id: I2631e8f936cab4cd376b2cc79b6b3b953440d4ec
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>