Update template deprecation to be more explicit (home-assistant#157965)

Author: Petro31

homeassistant/components/template/helpers.py

@@ -270,8 +270,6 @@ def create_legacy_template_issue(
         config.pop(CONF_PLATFORM, None)
         modified_yaml = format_migration_config(config)
         yaml_config = yaml_util.dump({DOMAIN: [{domain: [modified_yaml]}]})
-        # Format to show up properly in a numbered bullet on the repair.
-        yaml_config = "    ```\n    " + yaml_config.replace("\n", "\n    ") + "```"
     except RecursionError:
         yaml_config = f"{DOMAIN}:\n  - {domain}:      - ..."
 
@@ -287,6 +285,7 @@ def create_legacy_template_issue(
             "domain": domain,
             "breadcrumb": breadcrumb,
             "config": yaml_config,
+            "filename": "<filename>",
         },
     )
 

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\n1. Remove existing template definition.\n2. Add new template definition:\n{config}\n3. 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\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",
       "title": "Legacy {domain} template deprecation"
     }
   },