Update documentation around variables to clarify that every row needs a value for each variable

Description

As a (user), I need to understand that I can't leave a variable value empty in my spreadsheet or through the API so that I can avoid sending errors if I were to leave a variable empty.

WHY are we building? https://cds-snc.freshdesk.com/a/tickets/18429 A client ran into an error when trying to send a message with an empty value for a variable in their template WHAT are we building? A content update to our documentation for variables (API and UI) VALUE created by our solution Users won't run into errors/friction when trying to send

Other ideas out of scope: Allow optional variables. This is currently not possible and not on our roadmap at this time

Documentation and Artifacts

Good docs, figma mockups, ADRs, screenshots etc.

Acceptance Criteria

Given a Sender is sending a message using a template with a variable, when they fill in their spreadsheet or populate their variables using the API, then they know in advance that there must be a value for every variable for each message and that they can't leave a variable value empty.

[ ] Update the status of related findings, insights, and hypotheses on the Research Airtable
[ ] Once change/fix/feature is implemented, link relevant Airtable records to design artifacts (Figma)
A11y
Bilingualism
Measuring success and metrics

Related Research Airtable records

(find stuff yourself)

QA Steps

[ ] Tested in a realistic production scenario

GC Articles Publish checklist

[ ] Supporting feature is released and unflagged
[ ] Create or update slug
[ ] Page content and slug is translated
[ ] Document links to and from the page
[ ] Add page slug and title to inventory
[ ] If new page, add WAF rule
[ ] Create new page or update existing page content
[ ] Create or update translation to the page
[ ] Link translations by choosing an assigned translation
[ ] If new page, save as draft
[ ] If existing page, update the page
[ ] Post page in Slack for last minute reviews
[ ] On staging: Clear the cache through GC Notify's admin panel
[ ] On staging: Check links, images and language toggle
[ ] Give a heads up to the app-team channel once ready to publish
[ ] On staging and production: Clear the cache through GC Notify's admin panel

cds-snc / notification-planning