fix typo (#7832)

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/7832

Reviewed By: jay-zhuang

Differential Revision: D25785459

Pulled By: zhichao-cao

fbshipit-source-id: 78658dcb5a5f24141395046f74d7d57f11ad0868

utilities/fault_injection_fs.cc

@@ -9,7 +9,7 @@
 
 // This test uses a custom FileSystem to keep track of the state of a file
 // system the last "Sync". The data being written is cached in a "buffer".
-// Only when "Sync" is called, the data will be persistent. It can similate
+// Only when "Sync" is called, the data will be persistent. It can simulate
 // file data loss (or entire files) not protected by a "Sync". For any of the
 // FileSystem related operations, by specify the "IOStatus Error", a specific
 // error can be returned when file system is not activated.