docs: fix a typo

Closes #150

src/civil/date.rs

@@ -1236,7 +1236,7 @@ impl Date {
     ///
     /// # Example
     ///
-    /// This example shows how to created a zoned value with a fixed time zone
+    /// This example shows how to create a zoned value with a fixed time zone
     /// offset:
     ///
     /// ```

src/civil/datetime.rs

@@ -1388,7 +1388,7 @@ impl DateTime {
     ///
     /// # Example
     ///
-    /// This example shows how to created a zoned value with a fixed time zone
+    /// This example shows how to create a zoned value with a fixed time zone
     /// offset:
     ///
     /// ```

src/timestamp.rs

@@ -1082,7 +1082,7 @@ impl Timestamp {
     ///
     /// # Example
     ///
-    /// This example shows how to created a zoned value with a fixed time zone
+    /// This example shows how to create a zoned value with a fixed time zone
     /// offset:
     ///
     /// ```