Add example for hmac

[Firstyear]

Relates to #21 - This adds an example of how to create a loadable hmac key.

[ionut-arm]

Thanks for the patch! The example looks useful overall, left a few small clarity-related comments

[Firstyear]

Hey @ionut-arm I think I've resolved everything here. Is this good to go now? I wanted to start to add some more examples soon :)

[ionut-arm]

Ah, apologies! One more thing that would be needed is to address the clippy and formatting errors that are failing the CI. It might be needed to rebase on top of main to get everything green, I think there are some fixes there for some clippy issues.

[Firstyear]

All good, happy to do that today. Didn't know if the project wanted me to run fmt/clippy :)

[Superhepper]

Thanks a lot for the PR. I think it looks good.

Don't forget that all the commits in the PR needs to be signed otherwise the DCO check will fail.

[Firstyear]

Thank you for reviewing! I plan to add more examples and might need some more help and advice in the process :)

[wiktor-k]

All good, happy to do that today. Didn't know if the project wanted me to run fmt/clippy :)

I think it'd be best if you just squashed all commits, rebased on top of master, and added Signed-off-by line to that single commit.

I'm on mobile so it's hard to me to find a one liner to do that but if you have problems please say we may collectively find something :)

[Firstyear]

Done!