Fix typo in feedReplicationBacklog() top comment.

src/replication.c

@@ -122,7 +122,7 @@ void freeReplicationBacklog(void) {
 /* Add data to the replication backlog.
  * This function also increments the global replication offset stored at
  * server.master_repl_offset, because there is no case where we want to feed
- * the backlog without incrementing the buffer. */
+ * the backlog without incrementing the offset. */
 void feedReplicationBacklog(void *ptr, size_t len) {
     unsigned char *p = ptr;