activate linkcheck for external links

book.toml

@@ -22,6 +22,8 @@ runnable = false
 "/core_concepts/microchains.html" = "/developers/core_concepts/microchains.html"
 
 [output.linkcheck]
+follow-web-links = true
+exclude = [ 'x\.com', 'crates\.io' ]
 
 [build]
 build-dir = "book"

src/developers/sdk/composition.md

@@ -7,7 +7,7 @@ This section is about calling other applications using _cross-application
 calls_.
 
 Such calls happen on the same chain and are made with the
-[`ContractRuntime::call_application`](https://docs.rs/linera-sdk/latest/linera_sdk/struct.ContractRuntime.html#call_application)
+[`ContractRuntime::call_application`](https://docs.rs/linera-sdk/latest/linera_sdk/contract/type.ContractRuntime.html#call_application)
 method:
 
 ```rust,ignore

src/developers/sdk/messages.md

@@ -10,11 +10,11 @@ may be different.
 
 For your application, you can specify any serializable type as the `Message`
 type in your `Contract` implementation. To send a message, use the
-[`ContractRuntime`](https://docs.rs/linera-sdk/latest/linera_sdk/struct.ContractRuntime.html)
-made available as an argument to the contract's [`Contract::load`] constructor.
+[`ContractRuntime`](https://docs.rs/linera-sdk/latest/linera_sdk/contract/type.ContractRuntime.html)
+made available as an argument to the contract's [`Contract::load`](https://docs.rs/linera-sdk/latest/linera_sdk/trait.Contract.html#tymethod.load) constructor.
 The runtime is usually stored inside the contract object, as we did when
 [writing the contract binary](./contract.md). We can then call
-[`ContractRuntime::prepare_message`](https://docs.rs/linera-sdk/latest/linera_sdk/struct.ContractRuntime.html#prepare_message)
+[`ContractRuntime::prepare_message`](https://docs.rs/linera-sdk/latest/linera_sdk/contract/type.ContractRuntime.html#prepare_message)
 to start preparing a message, and then
 [`send_to`](https://docs.rs/linera-sdk/latest/linera_sdk/struct.MessageBuilder.html#send_to)
 to send it to a destination chain.