Fixed typo

src/main/asciidoc/concepts/transactions.adoc

@@ -151,7 +151,7 @@ ArcadeDB has different levels of durability based on storage type, configuration
 
 This mode uses the well known Multi Version Control System http://en.wikipedia.org/wiki/Multiversion_concurrency_control[MVCC] by allowing multiple reads and writes on the same records.
 The integrity check is made on commit.
-If the record has been saved by another transaction in the interim, then an `OConcurrentModificationException` will be thrown.
+If the record has been saved by another transaction in the interim, then an `ConcurrentModificationException` will be thrown.
 The application can choose either to repeat the transaction or abort it.
 
 NOTE: ArcadeDB keeps the whole transaction on client's RAM, so the transaction size is affected by the available RAM (Heap) memory on JVM.