I recently made a library for bevy, and want it to be available under the same dual license as bevy. What i've done is created both licence files and copy-pasted the contents, as well as copy the license sections from another bevy project. Is this all I need to do? I'm not a lawyer and am very new to all of this.
I'm also not a lawyer, but including both license files and adding to your README that your project is dual-licensed under both licenses at the user's choice should be sufficient.
GitHub should also detect both licenses and show them in the project's side bar.
If you copy-pasted the licenses, just make sure to adapt the MIT license, as it includes the year and name of the copyright holder.
You should adapt these to your project.
Fun fact: On GitHub, if you add a file in the web UI and include "LICENSE" in the file name, it gives you a button to choose a license template.
Then you can see common license options and a summary of what they do. It also allows you to fill in details like the year and copyright holder.