Fix function comments errors (#3226)

Fix typos

linera-execution/src/runtime.rs

@@ -331,7 +331,7 @@ impl<UserInstance> SyncRuntimeInternal<UserInstance> {
             .expect("Call stack is unexpectedly empty")
     }
 
-    /// Returns a mutable refernce to the [`ApplicationStatus`] of the current application.
+    /// Returns a mutable reference to the [`ApplicationStatus`] of the current application.
     ///
     /// The current application is the last to be pushed to the `call_stack`.
     ///

linera-indexer/plugins/src/template.rs

@@ -28,7 +28,7 @@ impl Template<C> {
 
     // Private functions are directly applied to the `Template` struct.
     async fn helper1(&self, ...) -> Result<.., IndexerError> {
-        // handle some thinfs on the `Template` struct
+        // handle some things on the `Template` struct
     }
 
     // Public functions are the ones accessible through the GraphQL server.

linera-rpc/src/simple/transport.rs

@@ -241,7 +241,7 @@ where
         }
     }
 
-    /// Creates a [`UpdServer`] bound to the provided `address`, handling messages using the
+    /// Creates a [`UdpServer`] bound to the provided `address`, handling messages using the
     /// provided `handler`.
     async fn bind(address: impl ToSocketAddrs, handler: State) -> Result<Self, std::io::Error> {
         let socket = UdpSocket::bind(address).await?;