Add append method to interact with the service

[JarosLucky]

An append is a very specific and useful method to save the number of queries for data that is regularly updated. For example, logs, transactions, or similar.They take up a lot of space, require regular updates, etc. If you transfer logs via express, the data almost instantly becomes irrelevant and takes up space.The goal is to be able to create a key that will live like any normal one, but can be supplemented during its lifetime. And when the client needs it, he will be able to download the data at any time, without having to request new data from the server with subsequent downloading.

[sarahsturgeon]

I could possibly add support for an AppendRaw function. It simply couldn't work with compression.

As I continue building out v1 revision 2 I'll see if there's a sensible place to put it 👍