gca-create-relation.php: Added snippete demonstrating how to create a relation with GCA.

[veryspry]

Context

⛑️ Ticket(s): https://secure.helpscout.net/conversation/2768092049/74169?viewId=6987275

Summary

Adds a snippet to demonstrate how to create a Relation in Airtable while processing a GC Airtable Feed.

Relies on: https://github.com/gravitywiz/gc-airtable/pull/4

[github-actions]

	Warnings
⚠️	When ready, don't forget to request reviews on this pull request from your fellow wizards.

Generated by 🚫 dangerJS against cbe0d9b

[claygriffiths]

I'd denote this as an experimental snippet, since it requires a specific configuration.

Before making this non-experimental, I'd convert it to a class-based snippet which would help make configuration easier and allow for more relationships.

[veryspry]

I'd denote this as an experimental snippet, since it requires a specific configuration.

Before making this non-experimental, I'd convert it to a class-based snippet which would help make configuration easier and allow for more relationships.

Sounds good!

I updated the header here cbe0d9b