Chore: Add slug and tags to config.json (#142)

Closes #118
Closes #137

config.json

@@ -471,6 +471,54 @@
     ]
   },
   "concepts": [],
-  "key_features": [],
-  "tags": []
+  "key_features": [
+    {
+      "title": "Expressive",
+      "content": "Support for multiple programming paradigms, with strong metaprogramming capabilities.",
+      "icon": ""
+    },
+    {
+      "title": "Fast",
+      "content": "D programs are compiled, leading to faster execution times than interpreted languages.",
+      "icon": ""
+    },
+    {
+      "title": "Safe",
+      "content": "Functions tagged as @safe restrict them to a memory-safe subset of D.",
+      "icon": ""
+    },
+    {
+      "title": "Language Interop",
+      "content": "Seamlessly embed C and C++ into your D projects, giving you access to millions of libraries.",
+      "icon": ""
+    },
+    {
+      "title": "Better C",
+      "content": "Integrate D into C projects using the -betterC compilation flag.",
+      "icon": ""
+    },
+    {
+      "title": "Optional GC",
+      "content": "Leave it enabled when it's needed, and disable it when it's not.",
+      "icon": ""
+    }
+  ],
+  "tags": [
+    "paradigm/functional",
+    "paradigm/imperative",
+    "paradigm/object_oriented",
+    "typing/static",
+    "typing/strong",
+    "execution_mode/compiled",
+    "platform/windows",
+    "platform/mac",
+    "platform/linux",
+    "used_for/backends",
+    "used_for/cross_platform_development",
+    "used_for/embedded_systems",
+    "used_for/financial_systems",
+    "used_for/games",
+    "used_for/guis",
+    "used_for/scientific_calculations"
+  ]
 }