in demo page, open api doc link in new tab

demo/index.html

@@ -19,7 +19,7 @@
         <h1>malle demo page</h1>
         <h2>API documentation</h2>
         <p>If you are looking for the complete API documentation, with all possible options and interfaces with their description, it is available here:</p>
-        <a href='/malle/api'><button class='btn btn-primary'>Complete API documentation</button></a>
+        <a href='/malle/api' target='_blank'><button class='btn btn-primary'>Complete API documentation</button></a>
         <h2>Minimal example</h2>
         <p>The text <span id='minimal' class='fw-bold'>in bold</span> is malleable. Try clicking on it.</p>
         <h2>Selecting input type</h2>