doc: add text to links

Some links were empty and hence did not appear in the generated
documentation.

Documentation/release/9.4/support-runtime-opengl-window-selection.md

@@ -6,10 +6,10 @@ In case the system is not configured for `EGL`, VTK will fallback to OSMesa. The
 Similarly on Windows, VTK will now automatically fallback to OSMesa if the OpenGL drivers on Windows system are too old i,e do not
 support OpenGL 3.2 or higher.
 
-You can learn about the new behavior of the OpenGL build settings in [](https://docs.vtk.org/en/latest/build_instructions/build_settings.html#opengl-related-build-options)
+You can learn about the new behavior of the OpenGL build settings in [OpenGL related build options](https://docs.vtk.org/en/latest/build_instructions/build_settings.html#opengl-related-build-options)
 
 To enable runtime selection, VTK now integrates the modern OpenGL loader library [glad](https://github.com/Dav1dde/glad) as a [third-party project](/developers_guide/git/thirdparty-projects.md), replacing `glew`, which did not support compiling both `GLX` and `EGL` in the same build
 
 If OSMesa is not installed, VTK prints a warning to the console and suggests installing OSMesa.
 
-You can enforce a specific render window by setting the `VTK_DEFAULT_OPENGL_WINDOW` environment variable. See [](https://docs.vtk.org/en/latest/advanced/runtime_settings.html#opengl).
+You can enforce a specific render window by setting the `VTK_DEFAULT_OPENGL_WINDOW` environment variable. See [Runtime settings - OpenGL](https://docs.vtk.org/en/latest/advanced/runtime_settings.html#opengl).