Iron Vault supports Truths through three main features: Truth Blocks, the Generate Truths command, and its Rulesets and Homebrew capabilities.
In summary, the experience is that you first use the Generate Truths command to create a Truths file somewhere in your vault, then you interact with the generated Truth Blocks to pick each truth. The Truths file will be populated according to the Truths outlined in your active Rulesets and Homebrew.
Once the Truths file is generated and your Truths are picked, you're free to edit the file however you wish, even split it up into multiple files if that's what you prefer. You can carry around the Truth Block along with it, and it'll Just Work.
For more information on the process of picking your truths, see the Truth Blocks example and its documentation.