[ci skip] Merge pull request #4986 from ka7/feature/spelling

Spelling fixes in comment blocks and docs
diff --git a/system/database/drivers/oci8/oci8_driver.php b/system/database/drivers/oci8/oci8_driver.php
index c7f0330..fb2f6b3 100644
--- a/system/database/drivers/oci8/oci8_driver.php
+++ b/system/database/drivers/oci8/oci8_driver.php
@@ -553,7 +553,7 @@
 	 * Error
 	 *
 	 * Returns an array containing code and message of the last
-	 * database error that has occured.
+	 * database error that has occurred.
 	 *
 	 * @return	array
 	 */