Removed boilerplates from library and test targets.

Sources/DocCMiddleware/hummingbird_docc_middleware.swift

@@ -1,2 +0,0 @@
-// The Swift Programming Language
-// https://docs.swift.org/swift-book

Tests/DocCMiddleware/hummingbird_docc_middlewareTests.swift

@@ -1,7 +0,0 @@
-import Testing
-
-@testable import DocCMiddleware
-
-@Test func example() async throws {
-    // Write your test here and use APIs like `#expect(...)` to check expected conditions.
-}