Mermaid diagrams: remove the yellow fill, add missing tutorial diagrams

[paolosalvatori]

Motivation

Every mermaid diagram in the repository rendered its subgraphs with mermaid's default cluster fill, #ffffde, a pale yellow that looks wrong on GitHub in both light and dark themes.

Several tutorials also had no diagram at all, so the only way to understand their topology was to read the script list.

Changes

The yellow is gone. All five existing diagrams (three KEDA tutorials, the Terraform and Bicep tags/labels/taints tutorials) now carry one directive:

%%{init: {'themeVariables': {'clusterBkg': 'transparent', 'clusterBorder': '#8c8c8c'}}}%%

transparent rather than white on purpose: a subgraph then takes the page background, so it reads correctly in GitHub's dark theme as well, while keeping its border and label.

Two new diagrams, for the tutorials that had none:

• tutorials/ccm/scripts: the cloud controller manager watching Service objects and reconciling the kubernetes and kubernetes-internal load balancers, the public IP and the NSG rule in the node resource group, then writing EXTERNAL-IP back.
• tutorials/gateway-api/scripts: the managed add-on supplying only the CRDs, NGINX Gateway Fabric claiming the nginx GatewayClass and provisioning a per-Gateway data plane, and the request path through the port-forward to the echo-server Service.

Testing

Every mermaid block in the repository was extracted and rendered with the mermaid CLI before committing, because a diagram that does not compile is worse than no diagram. 7 of 7 render, and grepping the rendered SVGs for #ffffde now returns nothing (it returned 5 hits before).

The renderer runs in a container (minlag/mermaid-cli), since the host mmdc has no Chrome available.

More tutorial diagrams (the KEDA index, Key Vault CSI driver, and the network-policy tutorials) are on the way as follow-up commits to this branch.

[Copilot]

Pull request overview

This PR improves tutorial documentation by standardizing Mermaid diagram styling to remove Mermaid’s default yellow subgraph fill (improving GitHub light/dark theme rendering) and by adding missing architecture diagrams to tutorials that previously lacked them.

Changes:

• Added a Mermaid init directive to existing diagrams to make cluster backgrounds transparent and set a consistent cluster border color.
• Added new “Architecture” sections with Mermaid diagrams to the CCM scripts tutorial and the Gateway API scripts tutorial.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
tutorials/terraform/tags-labels-taints/README.md	Adds Mermaid theme init directive to remove default cluster fill.
tutorials/keda/service-bus/README.md	Adds Mermaid theme init directive to remove default cluster fill.
tutorials/keda/queue-storage/README.md	Adds Mermaid theme init directive to remove default cluster fill.
tutorials/keda/event-hubs/README.md	Adds Mermaid theme init directive to remove default cluster fill.
tutorials/gateway-api/scripts/README.md	Adds an Architecture section with a new Mermaid diagram + theme init directive.
tutorials/ccm/scripts/README.md	Adds an Architecture section with a new Mermaid diagram + theme init directive.
tutorials/bicep/tags-labels-taints/README.md	Adds Mermaid theme init directive to remove default cluster fill.

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