[web] Added documentation on xml patch and include.

Documentation/ProjectFile/i_ProjectFile.md

web/config/_default/config.toml

web/content/docs/userguide/basics/container.md

web/content/docs/userguide/basics/project-file.md

...content/docs/userguide/post-processing/paraview-on-eve.md

...ide/process-dependent-configuration/Heat_Transport_BHE.md

...ndent-configuration/Heat_Transport_BHE_PipelineNetwork.md

web/content/docs/userguide/troubleshooting/general.md

web/content/docs/userguide/troubleshooting/get-support.md

web/content/docs/userguide/troubleshooting/project-file.md