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

Spelling fixes in comment blocks and docs
diff --git a/system/database/drivers/mssql/mssql_driver.php b/system/database/drivers/mssql/mssql_driver.php
index f0cfb2f..f76d127 100644
--- a/system/database/drivers/mssql/mssql_driver.php
+++ b/system/database/drivers/mssql/mssql_driver.php
@@ -352,7 +352,7 @@
 	 * Error
 	 *
 	 * Returns an array containing code and message of the last
-	 * database error that has occured.
+	 * database error that has occurred.
 	 *
 	 * @return	array
 	 */