add api documentation page

commafeed-client/src/pages/app/ApiDocumentationPage.tsx

@@ -0,0 +1,12 @@
+import { Loader } from "components/Loader"
+import React, { Suspense } from "react"
+
+export function ApiDocumentationPage() {
+    // swagger-ui is very large, load only on-demand
+    const SwaggerUI = React.lazy(() => import("swagger-ui-react"))
+    return (
+        <Suspense fallback={<Loader />}>
+            <SwaggerUI url="swagger/swagger.json" />
+        </Suspense>
+    )
+}