Removing python 2 reference in BuildGuide

As python 2 support ends, removing its rereferences from buildguide

Issue-ID: OOM-2345

Signed-off-by: Tomáš Levora <t.levora@partner.samsung.com>
Change-Id: I1130fd15af21d3e5a8bb80228d4cb31b5d25e41d
1 file changed