fix typos README.md
fix typos README.md

I think these are typos.
Please check.
loveshell/skydns,weekface/skydns,tuannvm/skydns,zvelo/zvelo-skydns,erimatnor/skydns-kubernetes,yonglehou/skydns,andrewrothstein/skydns,vinhhrv/skydns,nicescale/skydns,netf/skydns,AdoHe/skydns,hw-qiaolei/skydns,zhang0137/skydns,tonicbupt/skydns,smarterclayton/skydns,skynetservices/skydns,ZeaLoVe/skydns,no2key/skydns