Broken relative link due to the branch name being inferred incorrectly

[nacnudus]

The final link in the body text of this page is broken, because it uses main instead of master.

• Incorrect: https://github.com/alphagov/govuk-aws/blob/main/terraform/projects/infra-google-monitoring
• Correct: https://github.com/alphagov/govuk-aws/blob/master/terraform/projects/infra-google-monitoring

(tree instead of blob would be even more correct, but GitHub rewrites/redirects it anyway.)

The tech docs template implies that master is the default, so I don't understand why the relative path in the source code is being resolved to main.

https://github.com/alphagov/govuk-aws/blob/92826e9a2c97d80c97e6501127532c38510655ea/docs/guides/deploying-google-terraform.md?plain=1#L115