feat: visibility.md

docs/uni-app-x/css/visibility.md

+<!-- CSSJSON.visibility.name -->
+
+<!-- CSSJSON.visibility.description -->
+
+<!-- CSSJSON.visibility.syntax -->
+
+<!-- CSSJSON.visibility.values -->
+
+<!-- CSSJSON.visibility.compatibility -->
+
+<!-- CSSJSON.visibility.reference -->
\ No newline at end of file