Standardise headings

[charlesyoung]

Page headings should be as below.

Datasets noted as Dataset on the page heading
Documents noted as Document on the page heading
Organisations and Help seems fine
Analysis is displayed in a completed different way

[mattfullerton]

@moman822 Can you decide how to deal with the analysis issue? I'll do the others together with #140

[mattfullerton]

@moman822 I think Analysis is covered well enough by #176 and doesn't require any action on your part right now