Address review comments

src/olm/session/double_ratchet.rs

@@ -23,6 +23,8 @@ use super::{
     receiver_chain::ReceiverChain,
     root_key::{RemoteRootKey, RootKey},
 };
+#[cfg(doc)]
+use crate::olm::session::receiver_chain::ReceiverChain;
 use crate::olm::{messages::Message, shared_secret::Shared3DHSecret};
 
 /// The sender side of a double-ratchet implementation.
@@ -34,12 +36,12 @@ use crate::olm::{messages::Message, shared_secret::Shared3DHSecret};
 /// the *next* root key).
 ///
 /// Once we receive a message, we transition to the "inactive" state. Since we
-/// don't handle decryption here (that's done in
-/// [`crate::olm::session::ChainStore`]), we don't need to keep track of the
-/// sender's chain key. All we need is enough state so that we can calculate the
-/// next root key once we start encrypting again: specifically, the public part
-/// of the other side's ratchet key `T`<sub>`i`</sub> which was sent to us in
-/// the message, and the remote root key `R`<sub>`i`</sub>.
+/// don't handle decryption here (that's done in [`ReceiverChain`]), we don't
+/// need to keep track of the sender's chain key. All we need is enough state so
+/// that we can calculate the next root key once we start encrypting again:
+/// specifically, the public part of the other side's ratchet key
+/// `T`<sub>`i`</sub> which was sent to us in the message, and the remote root
+/// key `R`<sub>`i`</sub>.
 #[derive(Serialize, Deserialize, Clone)]
 #[serde(transparent)]
 pub(super) struct DoubleRatchet {