add http headers via vercel.json, update theme demo url

theme.toml

@@ -3,7 +3,7 @@ description = "📚 Minimal is a Zola port of the Jekyll theme with the same nam
 license = "MIT"
 homepage = "https://github.com/semanticdata/zola-minimal/"
 min_version = "0.18.0"
-demo = "https://semanticdata.github.io/zola-minimal/"
+demo = "https://zola-minimal.vercel.app/"
 
 [extra]
 

vercel.json

@@ -0,0 +1,33 @@
+{
+  "headers": [
+    {
+      "source": "/(.*)",
+      "headers": [
+        {
+          "key": "Content-Security-Policy",
+          "value": "script-src 'self' 'unsafe-inline'"
+        },
+        {
+          "key": "X-Frame-Options",
+          "value": "DENY"
+        },
+        {
+          "key": "X-Content-Type-Options",
+          "value": "nosniff"
+        },
+        {
+          "key": "Referrer-Policy",
+          "value": "strict-origin-when-cross-origin"
+        },
+        {
+          "key": "Permissions-Policy",
+          "value": "accelerometer=(), ambient-light-sensor=(), autoplay=(), battery=(), camera=(), cross-origin-isolated=(), display-capture=(), document-domain=(), encrypted-media=(), execution-while-not-rendered=(), execution-while-out-of-viewport=(), fullscreen=(self), geolocation=(), gyroscope=(), keyboard-map=(), magnetometer=(), microphone=(), midi=(), navigation-override=(), payment=(), picture-in-picture=(self), publickey-credentials-get=(), screen-wake-lock=(), sync-xhr=(self), usb=(), web-share=(self), xr-spatial-tracking=(), clipboard-read=(self), clipboard-write=(self), gamepad=(), speaker-selection=(self), conversion-measurement=(self), focus-without-user-activation=(), hid=(self), idle-detection=(), interest-cohort=(), serial=(), sync-script=()"
+        },
+        {
+          "key": "X-XSS-Protection",
+          "value": "1; mode=block"
+        }
+      ]
+    }
+  ]
+}