Add note about $router in navigation (#1304)
Add note about $router in navigation (#1304)

* Add note about $router in navigation

Closes #1136

* Update navigation.md

Alex-Sokolov/ru.vue-router,vuejs/vue-router,vuejs/vue-router,Alex-Sokolov/ru.vue-router,vuejs/vue-router,Alex-Sokolov/ru.vue-router