SEO: XSL article, SoftwareApplication schema, improve testing article

site/layouts/_default/baseof.html

@@ -10,6 +10,7 @@
   <meta property="og:description" content="{{ with .Description }}{{ . }}{{ else }}{{ .Site.Params.subtitle }}{{ end }}">
   <meta property="og:type" content="{{ if .IsPage }}article{{ else }}website{{ end }}">
   <meta property="og:url" content="{{ .Permalink }}">
+  {{ partial "schema-app.html" . }}
   {{ partial "adsense/head.html" . }}
   <link rel="stylesheet" href="{{ "css/main.css" | relURL }}">
 </head>

site/layouts/partials/schema-app.html

@@ -0,0 +1,26 @@
+<script type="application/ld+json">
+{
+  "@context": "https://schema.org",
+  "@type": "SoftwareApplication",
+  "name": "XSLT Playground",
+  "url": "https://xsltplayground.com",
+  "description": "Free online XSLT editor, tester and validator. Run XSLT 1.0, 2.0 and 3.0 transformations in your browser using Saxon. No install required.",
+  "applicationCategory": "DeveloperApplication",
+  "operatingSystem": "Any",
+  "offers": {
+    "@type": "Offer",
+    "price": "0",
+    "priceCurrency": "USD"
+  },
+  "featureList": [
+    "XSLT 1.0, 2.0 and 3.0 support",
+    "Saxon-powered backend",
+    "Real-time XML transformation",
+    "XSLT validator with detailed error messages",
+    "Multiple workspaces",
+    "Execution trace and debugging",
+    "Multiple XML inputs and parameters",
+    "Import/Export workspaces as JSON"
+  ]
+}
+</script>