Out of order section of guide is potentially confusing

[trevoranderson]

The udl file introduction comes before the guidance on how to hook it up to the build. This is not a huge problem by itself, but the sentence

Note: If any of the things you expose in the udl file do not have an equivalent in your Rust crate, you will get a hard error. Try changing the u32 result type to u64 and see what happens!

is not true until that later step is complete. If you follow the guide up to the point and do the experiment as mentioned, there will be no errors because the .udl file is not incorporated into anything. This experimentation suggestion should be moved to later in the guide when it is actually illustrative.