Adding Stackmate to our BDK Users webpage

Hi there! I'm thunderbiscuit, I work on the core BDK team (mostly on language bindings). We're building a page on our website that includes projects that use BDK, and I'm reaching out to know if you'd be ok with us adding you there! You can take a look at the page with the current projects on our website here: https://bitcoindevkit.org/case-studies/

Thank you!
