The Associated Press Within the heart of the Navajo Nation and in the shadow of the sandstone arch that is the namesake of the tribal capitol, a simple greeting and big smiles were shared over and over again Friday as tribal officials gathered: “Yá‘át’ééh abíní!” It was a good morning indeed for Navajo President Buu Nygren as he signed legislation in Window Rock, Arizona, outlining a proposed water rights settlement that will ensure supplies from the Colorado River and other sources for three Native American tribes — as well as more security for drought-stricken Arizona. The signature came a day after the tribal council voted unanimously in favor of the measure. It also was approved this week by the San Juan Southern Paiute and Hopi tribes. Now, the three tribes…