typo: remove extra backtick in docs

Author: Bouncheck

manual/mapper/daos/getentity/README.md

@@ -89,7 +89,7 @@ The method can return:
 * a single entity instance. If the argument is a result set type, the generated code will extract
   the first row and convert it, or return `null` if the result set is empty.
 
-    ````java
+    ```java
     @GetEntity
     Product asProduct(Row row);