[web] Adapted to new structure: devguide.

web/content/docs/devguide/_index.md

web/content/docs/devguide/advanced/_index.md

web/content/docs/devguide/development-workflows/_index.md

web/content/docs/devguide/environments/_index.md

web/content/docs/devguide/getting-started/_index.md

...ocs/devguide/getting-started/build-configuration/index.md

...onfiguration_for_MPI_PETSc/configure_for_mpi_and_petsc.md

web/content/docs/devguide/getting-started/build/index.md

...ocs/devguide/getting-started/get-the-source-code/index.md

...ntent/docs/devguide/getting-started/introduction/index.md

...tent/docs/devguide/getting-started/prerequisites/index.md

web/content/docs/devguide/packages/_index.md

web/content/docs/devguide/procedures/_index.md

web/content/docs/devguide/testing/_index.md

web/content/docs/devguide/troubleshooting/_index.md