Implemented (a first version of) the DocCMiddleware middleware in the library target.

Library/Sources/Internal/Enumerations/StaticFile.swift

@@ -0,0 +1,21 @@
+enum StaticFile: String, CaseIterable {
+    case documentation = "documentation.json"
+    case faviconICO = "favicon.ico"
+    case faviconSVG = "favicon.svg"
+    case themeSettings = "theme-settings.json"
+}
+
+// MARK: - Pathable
+
+extension StaticFile: Pathable {
+    
+    // MARK: Computed
+    
+    var path: String {
+        switch self {
+        case .documentation: "/data/" + rawValue
+        default: .init(format: .Format.pathRoot, rawValue)
+        }
+    }
+    
+}