Advice on TemplateConfig and helm

docs/ref-template-cfg.md

@@ -128,6 +128,23 @@ For fields not specified in a ``TemplateConfig``, the corresponding
 template is unchanged -- the controller continues to use the template
 for VCL generation as currently defined.
 
+### Avoid templating in the wrong tool
+
+Because the VCL template is a go template, when using ``helm`` or
+other templating tools, care needs to be taken to avoid templating in
+that tool. [With helm, there are several options to achieve
+this](https://github.com/helm/helm/issues/2798), but then simplest
+might be to surround the VCL with ``{{` ... `}}``:
+
+```
+spec:
+  ingress: |
+    {{`
+    vcl 4.1;
+    #...
+    `}}
+```
+
 ### ``spec.ingress``
 
 ``spec.ingress`` specifies a template for genaration of VCL to