Updating page titles for template pages.

[nataliecarey]

Fix for #1952

[joelanman]

needs a changelog

[nataliecarey]

I've updated the titles and re-used them for the <h1> to ensure they're in sync.

[nataliecarey]

@joelanman I've made a few changes because I broke the highlight on the Templates nav item when I changed the title.

The title now includes - Templates as well as the page name e.g.

Page created - Templates - Manage your prototype - Service name goes here - GOV.UK Prototype Kit

It makes it pretty long, I can remove that if that's not wanted.

[joelanman]

I thought about it but it does make it long, and I think the titles are clear without it, I don't think we need 'Templates' in the title

[nataliecarey]

I've taken out the Templates - part of the title e.g.

Page created - Manage your prototype - Service name goes here - GOV.UK Prototype Kit

I've also added to the CHANGELOG.

[joelanman]

Nice work

[BenSurgisonGDS]

LGTM