Fix missing template key in deprecation repair (home-assistant#158033)

Author: Petro31

homeassistant/components/template/helpers.py

@@ -269,7 +269,9 @@ def create_legacy_template_issue(
     try:
         config.pop(CONF_PLATFORM, None)
         modified_yaml = format_migration_config(config)
-        yaml_config = yaml_util.dump({DOMAIN: [{domain: [modified_yaml]}]})
+        yaml_config = (
+            f"```\n{yaml_util.dump({DOMAIN: [{domain: [modified_yaml]}]})}\n```"
+        )
     except RecursionError:
         yaml_config = f"{DOMAIN}:\n  - {domain}:      - ..."
 

homeassistant/components/template/strings.json

@@ -529,7 +529,7 @@
       "title": "Deprecated battery level option in {entity_name}"
     },
     "deprecated_legacy_templates": {
-      "description": "The legacy `platform: template` syntax for `{domain}` is being removed. Please migrate `{breadcrumb}` to the modern template syntax.\n#### Step 1 - Remove legacy configuration\nRemove the `{breadcrumb}` template definition from the `configuration.yaml` `{domain}:` section.\n\n**Note:** If you are using `{domain}: !include {filename}.yaml` in `configuration.yaml`, remove the {domain} definition from the included `{filename}.yaml`.\n#### Step 2 -  Add the modern configuration\nAdd new template definition inside `configuration.yaml`:\n\n```{config}```\n\n**Note:** If there are any existing `template:` sections in your configuration, make sure to omit the `template:` line from the yaml above.  There can only be 1 `template:` section in `configuration.yaml`.  Also, ensure the indentation is aligned with the existing entities within the `template:` section.\n#### Step 3 - Restart Home Assistant or reload template entities",
+      "description": "The legacy `platform: template` syntax for `{domain}` is being removed. Please migrate `{breadcrumb}` to the modern template syntax.\n#### Step 1 - Remove legacy configuration\nRemove the `{breadcrumb}` template definition from the `configuration.yaml` `{domain}:` section.\n\n**Note:** If you are using `{domain}: !include {filename}.yaml` in `configuration.yaml`, remove the {domain} definition from the included `{filename}.yaml`.\n#### Step 2 -  Add the modern configuration\nAdd new template definition inside `configuration.yaml`:\n{config}\n**Note:** If there are any existing `template:` sections in your configuration, make sure to omit the `template:` line from the yaml above.  There can only be 1 `template:` section in `configuration.yaml`.  Also, ensure the indentation is aligned with the existing entities within the `template:` section.\n#### Step 3 - Restart Home Assistant or reload template entities",
       "title": "Legacy {domain} template deprecation"
     }
   },