Update VueRouter docs

[ikoevska]

From Vladimir Amiorkov via email:

Using the “nativescript-vue-template” proved that I cannot use the VueRouter, which stopped my development of the entire app. Now there is “VueRouter - routing (opt-in) - experimental!!” in the website but that was not there before, I did jump to the “Routing > Vue Router” page which still does not state any experiment tag or not supported.
Suggestion: It would be good if we can recommend something that can be used as “replacement” for the time being while the VueRouter is experimental. To me this sounds like the first time anyone creating a more advanced app with navigation will hit so we should suggest to him what is the “current best option” to implement navigation.

Tasks:

• State that support for Vue Router is experimental more clearly.
• Provide information how to implement navigation without using Vue Router. (Might need to be a separate topic?). (See the Manual Routing article.)

[ikoevska]

There clear disclaimers across the board that support is experimental.
There is now also a page about manual routing.

Let's close this and revisit if there are new reports about it.