improve downloader readme

cmd/txpool/readme.md

@@ -43,5 +43,4 @@ In `./build/bin/txpool --help` see flags: `--txpool.globalslots`, `--txpool.glob
 [] Add pool (db table) - where store recently mined txs - for faster unwind/reorg.
 [] Save history of local transactions - with 1 day expiration
 [] move tx.rlp field to separated map, to make tx immutable
-[] Fetcher.go - can’t work with multiple sentries (has single parseContext)