Adds link to lightning transaction crate

Author: Conor Okus

docs/.vuepress/config.js

@@ -78,7 +78,8 @@ const docsSidebar = [
           ['https://docs.rs/lightning-invoice/*/lightning_invoice/', 'lightning-invoice'],
           ['https://docs.rs/lightning-net-tokio/*/lightning_net_tokio/', 'lightning-net-tokio'],
           ['https://docs.rs/lightning-persister/*/lightning_persister/', 'lightning-persister'],
-          ['https://docs.rs/lightning-rapid-gossip-sync/*/lightning_rapid_gossip_sync/', 'lightning-rapid-gossip-sync']
+          ['https://docs.rs/lightning-rapid-gossip-sync/*/lightning_rapid_gossip_sync/', 'lightning-rapid-gossip-sync'],
+          ['https://docs.rs/lightning-transaction-sync/*/lightning_transaction_sync/', 'lightning-transaction-sync']
         ]
       },
       ['https://github.com/arik-so/SwiftLightning/tree/master/Documentation', 'Swift']