c8caee2b5e Document CompactTarget order/equality (Tobin C. Harding)
Pull request description:
Add documentation to the `CompactTarget` type explaining the nuance surrounding order/equality.
Close: #2110
ACKs for top commit:
apoelstra:
ACK c8caee2b5e
Tree-SHA512: c724b31ee620ff08d3c8b547250bc7067f875ef6cf4ce9efa082d5a9cfbd8b92620f86034e58caf573c479ce7aaa89bb7e9fa93dc356524663d3ecf583df3507