Add query segment example and documentation (#1417)

* fix a few new clippy lints

* Add query segment example

* Add trait documentation

* Change core package to root package

The core package contains the virtual dom implementation ([here](https://github.com/DioxusLabs/dioxus/tree/master/packages/core)). Root package might be a more clear way to refer to the main directory

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Co-authored-by: Evan Almloff <evanalmloff@gmail.com>

packages/router/src/routable.rs

@@ -22,7 +22,11 @@ impl<E: std::fmt::Display> std::fmt::Display for RouteParseError<E> {
     }
 }
 
-/// Something that can be created from a query string
+/// Something that can be created from a query string.
+///
+/// This trait needs to be implemented if you want to turn a query string into a struct.
+///
+/// A working example can be found in the `examples` folder in the root package under `query_segments_demo`
 pub trait FromQuery {
     /// Create an instance of `Self` from a query string
     fn from_query(query: &str) -> Self;