Fix 'botnet' checker: add hint about QCTF
Fix 'botnet' checker: add hint about QCTF

HackerDom/qctf-school-2015,HackerDom/qctf-school-2015,HackerDom/qctf-school-2015,HackerDom/qctf-school-2015,HackerDom/qctf-school-2015,HackerDom/qctf-school-2015,HackerDom/qctf-school-2015