add Dockerfile

[bijeebuss]

I want to use this for something I'm working on but I don't want to install rust on my machine. This Dockerfile allows somebody to build the project with
docker build -t nostr-tool .
and run it with
docker run nostr-tool nostr-tool -r wss://nostr.oxtr.dev text-note -c "Hello World"
If you have a docker account you could publish the image so that anybody could run it without cloning the repo or installing rust with almost the same command.

[bijeebuss]

I could just download the binary but having the cli in docker hub would make it easier to use as a composable app

[0xtrr]

Thanks for the contribution @bijeebuss, LGTM! Can you also add docker instructions to the readme under the Install section?

[0xtrr]

I'll also look into setting up an official docker image for nostr-tool on Dockerhub

[bijeebuss]

If you are interested I can add my .devcontainer in another PR. This would allow anybody to run the project directly from github by clicking "open in codespaces" or do development in a container without needing to install rust on their machine.

[0xtrr]

Cool, tbh I've never heard about .devcontainer and haven't used codespaces myself but I'm open to merge it if this is something that could be useful for someone.