Title of Ackn. section, BrE/AmE difference

[kopeckyf]

The title of the section Acknowledgements can have two different spellings:

• Acknowledgements (British, South African, NZ English)
• Acknowledgments (US English)

The British variant is pre-defined in our template and can cause inconsistencies when the chapter is written in American English. The problem does not arise for Canadian and Australian English because they accept both spellings.

At present, the only option to customise the heading is by hand, since we don't have a language setting on a per-chapter basis.