Rethink tags behaviour

https://nips.nostr.com/1

https://github.com/nostr-protocol/nips/issues/277
https://github.com/nostr-protocol/nips/blob/master/01.md
The idea of opening this issue is to standardize tags which are required for usage in the protocol.
In standard 1, it is mentioned that only one-letter tags can be searched. To improve discoverability and recognition of maker orders and replies, custom one-letter tags can be used.

Standard 57 gives an idea of using transaction receipts https://github.com/nostr-protocol/nips/blob/master/57.md.

For now it isn't critical, but just for further development.

Has to be discussed with Kyrylo together.
Just leaving it here so we don't forget.