docs: Simplify generation removing need for manual substitutions

Documentation/dev/git/develop_quickstart.md

Documentation/docs/advanced/.gitignore

Documentation/docs/advanced/build_documentation.md

Documentation/docs/advanced/build_for_mobile.md

Documentation/docs/advanced/build_python_wheels.md

Documentation/docs/advanced/build_wasm_emscripten.md

Documentation/docs/build_instructions/.gitignore

Documentation/docs/developers_guide/git/.gitignore

Documentation/docs/developers_guide/git/develop.md

Documentation/docs/developers_guide/git/test.md

Documentation/docs/vtk_documentation.py