Update documentation & add usage for UpdateScriptRepository

Refs #9574
Implement usage for NormaliseByPeakArea

Also clarify a property description
Refs #9574
Remove unrequired testcleanup sections

Refs #9574
Add hidden toctree to index.rst

This squashes all of the warnings about most documents not in a toctree.
Refs #9574
Add usage examples to DeleteWorkspace.

Refs #9574
Merge branch 'feature/9574_doc_check_and_usage' into develop