Original instructions available here - https://github.com/openshift/source-to-image
Execute build
IMAGE_NAME=singularo/s2i-shepherd-wordpress
docker build -t ${IMAGE_NAME} .
The builder image can also be created by using the make command since a Makefile is included.
Now when you deploy from shepherd, it will use the updated singularo/s2i-shepherd-wordpress image with your changes.