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 capital, 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 settlement to ensure three Native American tribes have water rights from the Colorado River and other sources — and drought-stricken Arizona has more security in its supply. The signature came a day after the Navajo Nation Council voted unanimously in favor of the measure. The San Juan Southern Paiute and Hopi tribes also approved the settlement this week. Now, the three tribes in…