CCM-9305 child letter template, letter font change, email address & style fixes

[emmagifford]

Description

/using-nhs-notify/letter-templates changes:

• added 'Parent or guardian of' as the first line of the address block in the 'parent or guardian letter template' attachment
• replaced all of the letter template attachments with new templates that use Noto Sans as the main body text font, rather than Noto Sans Medium (new docs have an underscore at the end to differentiate them)
  -added 'mm' to first measurement in '(210 x 297mm)' (style fix)

Other changes:

• replaced email address england.nhsnotify@nhs.net with england.nhsnotifyonboarding@nhs.net in the last numbered step, at the top of all 4 template pages in /using-nhs-notify
• move full stops to outside of the hyperlinked text in the numbered steps at the top of all template pages (style fix)
• in /using-nhs-notify/nhs-app-templates, there was a rogue 'email' typo in 'If the recipient is not expecting to receive an email from you' - replaced with 'message'

Context

Change to parent or guardian letter (also known as child letter) requested by Romy and Alex N as part of CCM-9305. The extra line in the address block still fits within the address window of the overlay.

The fix to the letter templates' fonts (Noto Sans Medium to Noto Sans) was just something I spotted and wanted to rectify while doing this PR.

The email address change was requested by Amina. Amina clarified that 'england.nhsnotify@nhs.net is only for expression of interest and wider enquiries. Then england.nhsnotifyonboarding@nhs.net is for the onboarding stuff so anything under 'using nhs notify'.

I spotted the /nhs-app-templates email typo on a call with Alex earlier and wanted to fix.

Type of changes

• Refactoring (non-breaking change)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would change existing functionality)
• Bug fix (non-breaking change which fixes an issue)

Checklist

• I am familiar with the contributing guidelines
• I have followed the code style of the project
• I have added tests to cover my changes
• I have updated the documentation accordingly
• This PR is a result of pair or mob programming

---

Sensitive Information Declaration

To ensure the utmost confidentiality and protect your and others privacy, we kindly ask you to NOT including PII (Personal Identifiable Information) / PID (Personal Identifiable Data) or any other sensitive data in this PR (Pull Request) and the codebase changes. We will remove any PR that do contain any sensitive information. We really appreciate your cooperation in this matter.

• I confirm that neither PII/PID nor sensitive data are included in this PR and the codebase changes.

[jakecosgrove]

All looks good, well done! :)