formatting(prettier): add json to conform

lua/409/plugins/formatting.lua

@@ -11,6 +11,7 @@ return {
 					typescript = { "prettierd" },
 					css = { "prettierd" },
 					svelte = { "prettierd" },
+					json = { "prettierd" },
 					dart = { "dart_format" },
 				},
 			}