typo fix: delete duplicate comment word (facebook#9249)

Summary:
typo fix: delete duplicate comment word

Pull Request resolved: facebook#9249

Reviewed By: riversand963

Differential Revision: D36219911

fbshipit-source-id: 01e2fda65590f18fe46eefb56e049e6f2d028ae8

include/rocksdb/env.h

@@ -796,7 +796,7 @@ class RandomAccessFile {
   // should return after all reads have completed. The reads will be
   // non-overlapping. If the function return Status is not ok, status of
   // individual requests will be ignored and return status will be assumed
-  // for all read requests. The function return status is only meant for any
+  // for all read requests. The function return status is only meant for
   // any errors that occur before even processing specific read requests
   virtual Status MultiRead(ReadRequest* reqs, size_t num_reqs) {
     assert(reqs != nullptr);