Add Prettier config to docs/sources

Author: oleiade

docs/sources/.prettierrc

@@ -0,0 +1,14 @@
+{
+  "singleQuote": true,
+  "quoteProps": "consistent",
+  "trailingComma": "es5",
+  "printWidth": 100,
+  "overrides": [
+    {
+      "files": ["**/*.md"],
+      "options": {
+        "parser": "babel"
+      }
+    }
+  ]
+}