Making GetOptions() comment better (#597)

include/rocksdb/db.h

@@ -485,7 +485,10 @@ class DB {
   // Get Env object from the DB
   virtual Env* GetEnv() const = 0;
 
-  // Get DB Options that we use
+  // Get DB Options that we use.  During the process of opening the
+  // column family, the options provided when calling DB::Open() or
+  // DB::CreateColumnFamily() will have been "sanitized" and transformed
+  // in an implementation-defined manner.
   virtual const Options& GetOptions(ColumnFamilyHandle* column_family)
       const = 0;
   virtual const Options& GetOptions() const {