Add 2020 Q4 financial transparency report

[lehnberg]

ref_balance checks out:

{
      "tx_hash": "5c75c669f4808b88a151b8e867a5aede075a0611f294c27365dd5b1fa9856913",
      "block_height": 662519,
      "tx_input_n": 0,
      "tx_output_n": -1,
      "value": 1000000000,
      "ref_balance": 9687264400,
      "confirmations": 12058,
      "confirmed": "2020-12-22T17:18:29Z",
      "double_spend": false
    }

https://api.blockcypher.com/v1/btc/main/addrs/bc1qecw954uappnwhle6tmafqskn6vxmpr6lmmuwfwldphfxplcshgnssy9kmx