[EN] Update documentation on how to manage templates

[aphilop]

The UI of the Settings > Metadata > Templates page will be implemented to follow the new design with the issues huridocs/uwazi#6771 and huridocs/uwazi#6740. The documentation needs to be updated to reflect the new changes.

Affected pages in English documentation to update:

• Administrator’s guide > BUILDING YOUR INFORMATION ARCHITECTURE
• CREATING ENTITY PAGES
• Administrator’s guide > CUSTOMISING YOUR COLLECTION’S DESIGN
• Administrator’s guide > VISUALISING & ANALYSING YOUR COLLECTION’S DATA