add contributing link to about refs #260
add contributing link to about refs #260

agrc/agrc.github.io,agrc/gis.utah.gov,agrc/agrc.github.io,agrc/gis.utah.gov,agrc/agrc.github.io,agrc/agrc.github.io,agrc/agrc.github.io,agrc/gis.utah.gov,agrc/gis.utah.gov,agrc/gis.utah.gov