Review: Improve comments

crates/matrix-sdk-crypto/src/identities/manager.rs

@@ -1965,7 +1965,7 @@ pub(crate) mod tests {
         assert!(!first_device.is_cross_signed_by_owner(&identity));
 
         let remember_previous_identity = other_identity.clone();
-        // We receive a new keys update for that user, with no identity anymore
+        // We receive updated keys for that user, with no identity anymore.
         // Notice that there is no server API to delete identity, but we want to test
         // here that a home server cannot clear the identity and serve a new one
         // after that would get automatically approved.

crates/matrix-sdk-crypto/src/identities/user.rs

@@ -606,7 +606,10 @@ impl ReadOnlyUserIdentity {
     ) -> Result<bool, SignatureError> {
         master_key.verify_subkey(&self_signing_key)?;
 
-        // The pin is maintained.
+        // We update the identity with the new master and self signing key, but we keep
+        // the previous pinned master key.
+        // This identity will have a pin violation until the new master key is pinned
+        // (see [`has_pin_violation`]).
         let pinned_master_key = self.pinned_master_key.read().unwrap().clone();
 
         let new = Self {