update comment

Author: dranikpg

src/core/compact_object.h

@@ -534,16 +534,16 @@ class CompactObj {
   union {
     uint8_t mask_ = 0;
     struct {
-      uint8_t ref : 1;  // Mark objects that have expiry timestamp assigned.
-      uint8_t expire : 1;
+      uint8_t ref : 1;      // Mark objects that don't own their allocation.
+      uint8_t expire : 1;   // Mark objects that have expiry timestamp assigned.
       uint8_t mc_flag : 1;  // Marks keys that have memcache flags assigned.
 
       // See the EncodingEnum for the meaning of these bits.
       uint8_t encoding : 2;
 
       // IO_PENDING is set when the tiered storage has issued an i/o request to save the value.
       // It is cleared when the io request finishes or is cancelled.
-      uint8_t io_pending : 1;  // also serves as async-delete for keys.
+      uint8_t io_pending : 1;
       uint8_t sticky : 1;
 
       // TOUCHED used to determin which items are hot/cold.