add comment about locals using shallow validation

internal/terraform/node_local.go

@@ -140,6 +140,10 @@ func (n *NodeLocal) References() []*addrs.Reference {
 func (n *NodeLocal) Execute(ctx EvalContext, op walkOperation) (diags tfdiags.Diagnostics) {
 	namedVals := ctx.NamedValues()
 	val, diags := evaluateLocalValue(n.Config, n.Addr.LocalValue, n.Addr.String(), ctx)
+	// We only use a shallow evaluation of deprecations here because we only want to warn
+	// if the entire value is deprecated. If e.g. a module is stored in the local and the module
+	// contains a deprecated output we don't want to warn about that here, but only when the
+	// output is actually referenced.
 	valWithoutDeprecations, deprecationDiags := ctx.Deprecations().Validate(val, n.ModulePath(), n.Config.Expr.Range().Ptr())
 	diags = diags.Append(deprecationDiags)