Fix pt-br.json

Small grammar mistake, for consistency.

lang/pt-br.json

@@ -7,7 +7,7 @@
     "category:car_amenities": "Equipamentos",
     "category:car_furniture": "Mobiliário urbano",
     "category:car_maxspeed": "Velocidade máxima",
-    "category:car_routes": "Rota rodoviária",
+    "category:car_routes": "Rotas rodoviárias",
     "category:children": "Equipamentos infantis",
     "category:communication": "Comunicação",
     "category:construction": "Terrenos vazios e obras",