fix typo

include/leveldb/comparator.h

@@ -14,7 +14,7 @@ namespace leveldb {
 class Slice;
 
 // A Comparator object provides a total order across slices that are
-// used as keys in an sstable or a database.  A Comparator implementation
+// used as keys in a sstable or a database.  A Comparator implementation
 // must be thread-safe since leveldb may invoke its methods concurrently
 // from multiple threads.
 class LEVELDB_EXPORT Comparator {