Add mainline,src repository [Official Page: http://nginx.org/en/linux_packages.html]

nginx.repo

# for CentOS 6
[nginx]
name=nginx repo
baseurl=http://nginx.org/packages/centos/6/$basearch/
gpgcheck=0
enabled=0

[nginx-src]
name=nginx SRPM repo
baseurl=http://nginx.org/packages/centos/6/SRPMS/
gpgcheck=0
enabled=0

[nginx-mainline]
name=nginx repo mainline
baseurl=http://nginx.org/packages/mainline/centos/6/$basearch/
gpgcheck=0
enabled=0

[nginx-mainline-src]
name=nginx SRPM repo mainline
baseurl=http://nginx.org/packages/mainline/centos/6/SRPMS/
gpgcheck=0
enabled=0