fix vcffilter docs
fix vcffilter docs

glennhickey/vcflib,wzugang/vcflib,harshinamdar/vcflib,tomdcsmith/vcflib,travc/vcflib,travc/vcflib,ashishjain1988/vcflib,travc/vcflib,ekg/vcflib,ekg/vcflib,zhmz90/vcflib,ashishjain1988/vcflib,harshinamdar/vcflib,glennhickey/vcflib,wzugang/vcflib,ashishjain1988/vcflib,ashishjain1988/vcflib,harshinamdar/vcflib,vcflib/vcflib,tomdcsmith/vcflib,vcflib/vcflib,glennhickey/vcflib,vcflib/vcflib,zhmz90/vcflib,wzugang/vcflib,harshinamdar/vcflib,vcflib/vcflib,ekg/vcflib,glennhickey/vcflib,zhmz90/vcflib,harshinamdar/vcflib,vcflib/vcflib,ekg/vcflib,zhmz90/vcflib,wzugang/vcflib,glennhickey/vcflib,vcflib/vcflib,zhmz90/vcflib,glennhickey/vcflib,vcflib/vcflib,ashishjain1988/vcflib,ekg/vcflib,ashishjain1988/vcflib,harshinamdar/vcflib,wzugang/vcflib,zhmz90/vcflib,tomdcsmith/vcflib,vcflib/vcflib,wzugang/vcflib