chore: fix some typos (#1997)

* Update events.rs

* Update transaction_extensions.rs

* Update mod.rs

* Update lib.rs

---------

Co-authored-by: James Wilson <james@jsdw.me>

core/src/events.rs

@@ -722,7 +722,7 @@ mod tests {
         let metadata = metadata::<Event>();
 
         // Encode our events in the format we expect back from a node, and
-        // construst an Events object to iterate them:
+        // construct an Events object to iterate them:
         let event1 = Event::A(1);
         let event2 = Event::B(true);
         let event3 = Event::A(234);