[web] Proper usage of menus.

web/config/_default/config.toml

web/content/books/bmb-2.pandoc

web/content/books/bmb-3.pandoc

web/content/books/bmb-4.pandoc

web/content/books/computational-geotechnics-i.pandoc

...omputational-hydrology-i-groundwater-flow-modeling.pandoc

web/content/books/computational-hydrology-ii.pandoc

web/content/books/computational-hydrology-iii.pandoc

web/content/books/geoenergy-modeling-i.pandoc

web/content/books/geoenergy-modeling-ii.pandoc

web/content/books/geoenergy-modeling-iii.pandoc

...ontent/books/models-of-thermochemical-heat-storage.pandoc

web/content/categories/books/_index.md

web/content/categories/tutorials/_index.md

web/content/docs/_index.pandoc

...ontent/docs/benchmarks/elliptic/elliptic-dirichlet.pandoc

...content/docs/devguide/getting-started/introduction.pandoc

web/content/docs/tools/getting-started/overview.pandoc

web/content/docs/userguide/basics/introduction.pandoc

web/content/publications/_index.pandoc