fix most typos, add crate-ci/typos to CI (#2653)

* fix most typos, add crate-ci/typos to CI

---------

Co-authored-by: Jonathan Kelley <jkelleyrtp@gmail.com>

examples/flat_router.rs

@@ -1,5 +1,5 @@
 //! This example shows how to use the `Router` component to create a simple navigation system.
-//! The more complex router example uses all of the router features, while this simple exmaple showcases
+//! The more complex router example uses all of the router features, while this simple example showcases
 //! just the `Layout` and `Route` features.
 //!
 //! Layouts let you wrap chunks of your app with a component. This is useful for things like a footers, heeaders, etc.