doc bind collision issue (#4394)
doc bind collision issue (#4394)

Signed-off-by: Chris O'Haver <c8d69f6e0f4a592980d82af78b0efddff3dcc387@infoblox.com>
yongtang/coredns,coredns/coredns,miekg/coredns,chrisohaver/coredns,miekg/coredns