[btcd] Update description on DockerHub from repository

[abitrolly]

Reticketed from bro-n-bro/cybernode#50 (comment)

• write description template and commit to images/fullnode-btcd
  • make sure btcd hash, patch level and image build date are present
  • add examples how to test btcd is working, how to access JSON-RPC (Story - bitcoind node for RPC requests #75)
• write script that updates description at cybernode/bitcoin-btcd
  • research re-using docker login

---

Description can be updated through PATCH request

curl 'https://hub.docker.com/v2/repositories/cyberfund/fullnode-btcd/' -X PATCH \
    -H 'Authorization: JWT ey...dw' \
    -H 'Origin: https://hub.docker.com' \
    -H 'Accept-Encoding: gzip, deflate, br' -H 'Accept-Language: en-US,en;q=0.8' \
    -H 'User-Agent: Mozilla/5.0 (X11; Linux x86_64)' \
    -H 'Content-Type: application/json' \
    -H 'Accept: application/json' \
    -H 'Referer: https://hub.docker.com/r/cyberfund/fullnode-btcd/' \
    -H 'Cookie: ajs_anonymous_id=%222... session_hint=1; token=ey...; csrftoken=bB' \
    -H 'Connection: keep-alive' \
    --data-binary '{"description":"Bitcoin fullnode based on btcd"}' \
    --compressed