Update readme.md
Update readme.md

Fixed typo.
codefortulsa/citygram,chriswhong/citygram,elberdev/citygram-nyc,shravan20084312/citygram,codeforamerica/citygram,BetaNYC/citygram-nyc,elberdev/citygram-nyc,shravan20084312/citygram,beetz12/citygram,openchattanooga/citygram,elberdev/citygram-nyc,beetz12/citygram,beetz12/citygram,codeforamerica/citygram,BetaNYC/citygram-nyc,BetaNYC/citygram-nyc,codefortulsa/citygram,chriswhong/citygram,shravan20084312/citygram,BetaNYC/citygram-nyc,codeforamerica/citygram,codeforamerica/citygram,codefortulsa/citygram,openchattanooga/citygram