fix: update kratos http courier jsonnet template sample (#1715)

Update 03_mail-courier-http.mdx

Author: vergil-zhao

docs/kratos/self-hosted/03_mail-courier-http.mdx

@@ -75,14 +75,14 @@ A universal Jsonnet template that works with all flows, would look like this:
 
 ```jsonnet
 function(ctx) {
-  recipient: ctx.Recipient,
-  template_type: ctx.TemplateType,
-  name: if "TemplateData" in ctx && "Identity" in ctx.TemplateData && "Name" in ctx.TemplateData.Identity then ctx.TemplateData.Identity.Name else null,
-  to: if "TemplateData" in ctx && "To" in ctx.TemplateData then ctx.TemplateData.To else null,
-  recovery_code: if "TemplateData" in ctx && "RecoveryCode" in ctx.TemplateData then ctx.TemplateData.RecoveryCode else null,
-  recovery_url: if "TemplateData" in ctx && "RecoveryURL" in ctx.TemplateData then ctx.TemplateData.RecoveryURL else null,
-  verification_url: if "TemplateData" in ctx && "VerificationURL" in ctx.TemplateData then ctx.TemplateData.VerificationURL else null,
-  verification_code: if "TemplateData" in ctx && "VerificationCode" in ctx.TemplateData then ctx.TemplateData.VerificationCode else null,
+  recipient: ctx.recipient,
+  template_type: ctx.template_type,
+  name: if "template_data" in ctx && "identity" in ctx.template_data && "name" in ctx.template_data.identity then ctx.template_data.identity.name else null,
+  to: if "template_data" in ctx && "to" in ctx.template_data then ctx.template_data.to else null,
+  recovery_code: if "template_data" in ctx && "recovery_code" in ctx.template_data then ctx.template_data.recovery_code else null,
+  recovery_url: if "template_data" in ctx && "recovery_url" in ctx.template_data then ctx.template_data.recovery_url else null,
+  verification_url: if "template_data" in ctx && "verification_url" in ctx.template_data then ctx.template_data.verification_url else null,
+  verification_code: if "template_data" in ctx && "verification_code" in ctx.template_data then ctx.template_data.verification_code else null,
 }
 
 ```