Router docs about set-only components

[Madoshakalaka]

Description

Router docs about set-only components.
Reword router docs,
use implementation on AttrValue instead of reimplementing.

Fixes #0000

Set-only access to the history is often needed. In some cases, the Router and the Switch components can do all the work listening and rendering different components.

Currently, the docs don't mention how to do it in the function component section. This can be done by calling BrowserHistory::default() which is part of the public API in the prelude. undocumented too ;)

@futursolo says he will work on a setter-only history API but probably won't make it to the 0.19 release. So I find it necessary to include it here.

Note the API in the future will probably still use the current BrowserHistory::default() implementation, but provide it as an AnyHistory instead, for compatibility to other environments.

Checklist

• I have run cargo make pr-flow
• I have reviewed my own code
• [NA] I have added tests

[github-actions]

Visit the preview URL for this PR (updated for commit 525fe36):

https://yew-rs--pr2214-router-docs-ou0tjprx.web.app

_{(expires Sun, 12 Dec 2021 02:08:48 GMT)}

_{🔥 via Firebase Hosting GitHub Action 🌎}