BTCP-Rebase/doc/release-notes-pr12823.md

Configuration sections for testnet and regtest

It is now possible for a single configuration file to set different options for different networks. This is done by using sections or by prefixing the option with the network, such as:

main.uacomment=bitcoin
test.uacomment=bitcoin-testnet
regtest.uacomment=regtest
[main]
mempoolsize=300
[test]
mempoolsize=100
[regtest]
mempoolsize=20

The addnode=, connect=, port=, bind=, rpcport=, rpcbind= and wallet= options will only apply to mainnet when specified in the configuration file, unless a network is specified.