message: txorphanage: comment improvements
diff: /** Guards orphan transactions and extra txs for compact blocks */
  extern RecursiveMutex g_cs_orphans;
  -/** Data structure to keep track of orphan transactions
  +/** A class to track orphan transactions (failed on TX_MISSING_INPUTS)
  + * Since we cannot distinguish orphans from bad transactions with
  + * non-existent inputs, we heavily limit the number of orphans
  + * we keep and the duration we keep them for.
  */
  class TxOrphanage {
  public:
  @@ -23,7 +26,9 @@ public:
  /** Check if we already have an orphan transaction (by txid or wtxid) */
  bool HaveTx(const GenTxid& gtxid) const EXCLUSIVE_LOCKS_REQUIRED(!g_cs_orphans);
  - /** Get the details of an orphan transaction (returns nullptr if not found) */
  + /** Get an orphan transaction and its orginating peer
  + * (Transaction ref will be nullptr if not found)
  + */
  std::pair<CTransactionRef, NodeId> GetTx(const uint256& txid) const EXCLUSIVE_LOCKS_REQUIRED(g_cs_orphans);
  /** Erase an orphan by txid */
  @@ -32,7 +37,7 @@ public:
  /** Erase all orphans announced by a peer (eg, after that peer disconnects) */
  void EraseForPeer(NodeId peer) EXCLUSIVE_LOCKS_REQUIRED(g_cs_orphans);
  - /** Erase all orphans included in / invalidated by a new block */
  + /** Erase all orphans included in or invalidated by a new block */
  void EraseForBlock(const CBlock& block) EXCLUSIVE_LOCKS_REQUIRED(!g_cs_orphans);
  /** Limit the orphanage to the given maximum */
  