[Docs] Fix dead link to the C++ Interop manifesto

Author: egorzhdan

docs/README.md

@@ -249,7 +249,7 @@ documentation, please create a thread on the Swift forums under the
     Describes the goals and design for Library Evolution.
 - [BuildManifesto.md](/docs/BuildManifesto.md):
   Provides an outline for modularizing the build system for the Swift toolchain.
-- [CppInteroperabilityManifesto.md](/docs/CppInteroperabilityManifesto.md):
+- [CppInteroperabilityManifesto.md](/docs/CppInteroperability/CppInteroperabilityManifesto.md):
   Describes the motivation and design for first-class Swift-C++ interoperability.
 - [DifferentiableProgramming.md](/docs/DifferentiableProgramming.md):
   Outlines a vision and design for first-class differentiable programming in Swift.