Refresh Rust language guide

[kate-goldenring]

We are coming up on conference season. Lets make sure we've walked through the Rust language guide before end of March

[FrankReh]

If someone would like the Rust guide to use the latest wasmtime release, v31, the porting suggesting from this PR is relevant (bytecodealliance/wasmtime#10016).

These changes were needed to move from v29 to v30, but the latest published release is v31.

diff --git a/component-model/examples/example-host/Cargo.toml b/component-model/examples/example-host/Cargo.toml
index b364a90..3aed8b7 100644
--- a/component-model/examples/example-host/Cargo.toml
+++ b/component-model/examples/example-host/Cargo.toml
@@ -10,5 +10,5 @@ Example Rust-based WebAssembly host that executes WebAssembly components
 anyhow = "1.0.72"
 async-std = { version = "1.13", features = ["attributes"] }
 clap = { version = "4", features = ["derive"] }
-wasmtime = "27.0"
-wasmtime-wasi = "27.0"
+wasmtime = "31.0"
+wasmtime-wasi = "31.0"
diff --git a/component-model/examples/example-host/src/state.rs b/component-model/examples/example-host/src/state.rs
index 74819bc..b13b4ba 100644
--- a/component-model/examples/example-host/src/state.rs
+++ b/component-model/examples/example-host/src/state.rs
@@ -1,5 +1,5 @@
 use wasmtime::component::ResourceTable;
-use wasmtime_wasi::{WasiCtx, WasiCtxBuilder, WasiView};
+use wasmtime_wasi::{IoView, WasiCtx, WasiCtxBuilder, WasiView};
 
 pub struct States {
     table: ResourceTable,
@@ -14,11 +14,13 @@ impl States {
     }
 }
 
-impl WasiView for States {
+impl IoView for States {
     fn table(&mut self) -> &mut ResourceTable {
         &mut self.table
     }
+}
 
+impl WasiView for States {
     fn ctx(&mut self) -> &mut WasiCtx {
         &mut self.ctx
     }