Help: Fix cmake-buildsystem(7) internal link

Fix a broken link from commit 987f3fa4e0 (Help: Add cmake-buildsystem(7)
subsections for each binary target type, 2024-12-12).

Help/manual/cmake-buildsystem.7.rst

@@ -137,7 +137,7 @@ then resolve remaining symbol dependencies by searching linked libraries.
 
   CMake expects shared libraries to export at least one symbol.  If a library
   does not export any unmanaged symbols, e.g., a Windows resource DLL or
-  C++/CLI DLL, make it a `Module Library <Module Libraries>`_ instead.
+  C++/CLI DLL, make it a `Module Library <Module Libraries_>`_ instead.
 
 .. _`Apple Frameworks`: