fix: v1 demo link (#6)

Author: motorina0

index.html

@@ -216,7 +216,7 @@ <h1 class="ud-hero-title" style="margin-bottom: 0px">
                 color="white"
                 text-color="black"
                 type="a"
-                href="https://v1.lnbits.com"
+                href="https://demo.lnbits.com"
                 label="Demo"
                 class="q-ml-sm"
                 size="lg"