message: handling invalid (wrong fork) headers: revise an unclear comment, and add additional comment
diff: @@ -6572,7 +6572,7 @@ bool ProcessMessage(CNode *pfrom, std::string strCommand, CDataStream &vRecv, in
  }
  }
  - // Check and accept each header in order from youngest block to oldest
  + // Check and accept each header in dependency order (oldest block to most recent)
  CBlockIndex *pindexLast = nullptr;
  int i = 0;
  for (const CBlockHeader &header : headers)
  @@ -6588,7 +6588,7 @@ bool ProcessMessage(CNode *pfrom, std::string strCommand, CDataStream &vRecv, in
  dosMan.Misbehaving(pfrom, nDos);
  }
  }
  -
  + // all headers from this one forward reference a fork that we don't follow, so erase them
  headers.erase(headers.begin() + i, headers.end());
  nCount = headers.size();
  break;
  