chore(doc): Replace futures crates with tokio-stream

examples/routeguide-tutorial.md

@@ -176,8 +176,6 @@ Edit `Cargo.toml` and add all the dependencies we'll need for this example:
 [dependencies]
 tonic = "0.9"
 prost = "0.11"
-futures-core = "0.3"
-futures-util = "0.3"
 tokio = { version = "1.0", features = ["rt-multi-thread", "macros", "sync", "time"] }
 tokio-stream = "0.1"
 
@@ -263,12 +261,11 @@ the package declared in our `.proto` file, not a filename, e.g "routeguide.rs".
 With this in place, we can stub out our service implementation:
 
 ```rust
-use futures_core::Stream;
 use std::pin::Pin;
 use std::sync::Arc;
 use tokio::sync::mpsc;
 use tonic::{Request, Response, Status};
-use tokio_stream::wrappers::ReceiverStream;
+use tokio_stream::{wrappers::ReceiverStream, Stream};
 ```
 
 ```rust
@@ -435,7 +432,7 @@ with information about their trip. As you can see, this time the method receives
 
 ```rust
 use std::time::Instant;
-use futures_util::StreamExt;
+use tokio_stream::StreamExt;
 ```
 
 ```rust
@@ -692,7 +689,6 @@ The client-side streaming method `record_route` takes a stream of `Point`s and r
 ```rust
 use rand::rngs::ThreadRng;
 use rand::Rng;
-use futures_util::stream;
 ```
 
 ```rust
@@ -706,7 +702,7 @@ async fn run_record_route(client: &mut RouteGuideClient<Channel>) -> Result<(),
     }
 
     println!("Traversing {} points", points.len());
-    let request = Request::new(stream::iter(points));
+    let request = Request::new(tokio_stream::iter(points));
 
     match client.record_route(request).await {
         Ok(response) => println!("SUMMARY: {:?}", response.into_inner()),
@@ -729,7 +725,7 @@ fn random_point(rng: &mut ThreadRng) -> Point {
 ```
 
 We build a vector of a random number of `Point` values (between 2 and 100) and then convert
-it into a `Stream` using the `futures::stream::iter` function. This is a cheap an easy way to get
+it into a `Stream` using the `tokio_stream::iter` function. This is a cheap an easy way to get
 a stream suitable for passing into our service method. The resulting stream is then wrapped in a
 `tonic::Request`.
 
@@ -830,4 +826,3 @@ On `cargo run`, this will generate code for the server only, and place the resul
 
 2) Similarly, we could also keep the `.proto` definitions in a separate crate and then use that
 crate as a direct dependency wherever we need it.
-