Fix broken Transaction link (fede1024#786)

Author: orslow

README.md

@@ -129,7 +129,7 @@ EOS is useful in read-process-write scenarios that require messages to be
 processed exactly once.
 
 To learn more about using transactions in rust-rdkafka, see the
-[Transactions](producer-transactions) section of the producer documentation.
+[Transactions][producer-transactions] section of the producer documentation.
 
 ### Users
 

src/lib.rs

@@ -121,7 +121,7 @@
 //! processed exactly once.
 //!
 //! To learn more about using transactions in rust-rdkafka, see the
-//! [Transactions](producer-transactions) section of the producer documentation.
+//! [Transactions][producer-transactions] section of the producer documentation.
 //!
 //! ### Users
 //!