Add skip_deploy_on_missing_secrets flags to documentation workflows

[xaviervia]

This is because the current documentation workflows deploy to external servers. Deploying requires secrets that are not available to pull requests coming from forks. This means that the pipeline for forks is now failing because it tries to do the deployment without having access to those secrets.

[github-actions[bot]]

Azure Static Web Apps: Your stage site is ready! Visit it here: https://mango-rock-0ef127a03-74.westeurope.azurestaticapps.net

[github-actions[bot]]

Azure Static Web Apps: Your stage site is ready! Visit it here: https://mango-rock-0ef127a03-74.westeurope.azurestaticapps.net

[github-actions[bot]]

Azure Static Web Apps: Your stage site is ready! Visit it here: https://jolly-stone-0d2f00e03-74.westeurope.azurestaticapps.net

[github-actions[bot]]

Azure Static Web Apps: Your stage site is ready! Visit it here: https://jolly-stone-0d2f00e03-74.westeurope.azurestaticapps.net