docs: Enhance output schema template property documentation

Improve the documentation for the `template` property in output schemas
by expanding the property description and adding a comprehensive
"Understanding templates" section that explains template processing,
syntax, and where generated URLs appear.

Changes:
- Enhanced template property description with Mustache syntax details
- Added "Understanding templates" section explaining:
  - How the platform processes templates (interpolation, generation, display)
  - Template syntax with concrete examples
  - Where templates appear (Console and API)

Addresses feedback from GitHub issue #2165.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: marcel-rbro

sources/platform/actors/development/actor_definition/output_schema/index.md

@@ -73,7 +73,7 @@ The output schema defines the collections of keys and their properties. It allow
 |----------------|--------------|--------------|-------------------------------------------------------------------------------------------------------------------------------------------------|
 | `title`        | string       | true         | The output's title, shown in the run's output tab if there are multiple outputs and in API as key for the generated output URL.                 |
 | `description`  | string       | false        | A description of the output. Only used when reading the schema (useful for LLMs)                                                                |
-| `template`     | string       | true         | Defines a template which will be translated into output URL. The template can use variables (see below)                                         |
+| `template`     | string       | true         | Defines a URL template that generates the output link. Templates use Mustache-style variable interpolation with {{variable}} syntax. The generated URL appears in the Apify Console Output tab and in the API response's output property. |
 
 ### Available template variables
 
@@ -90,6 +90,32 @@ The output schema defines the collections of keys and their properties. It allow
 | `run.defaultDatasetId`             | string | ID of the default dataset                                                                                                        |
 | `run.defaultKeyValueStoreId`       | string | ID of the default key-value store                                                                                                |
 
+## Understanding templates
+
+Templates allow you to dynamically generate URLs that point to your Actor's output. When an Actor run completes, the Apify platform processes each template by:
+
+1. **Variable interpolation**: Replacing `{{variable}}` placeholders with actual runtime values
+2. **URL generation**: Creating the final output URL
+3. **Display**: Showing the output in the Apify Console Output tab and including it in the API response
+
+### Template syntax
+
+Templates use Mustache-style double curly braces `{{variable}}` for variable interpolation. For example:
+
+- `{{links.apiDefaultDatasetUrl}}/items` becomes `https://api.apify.com/v2/datasets/<dataset-id>/items`
+- `{{run.containerUrl}}` becomes `https://<container-id>.runs.apify.net/`
+
+You can access nested properties using dot notation (e.g., `{{run.defaultDatasetId}}`, `{{links.publicRunUrl}}`).
+
+### Where templates appear
+
+The generated URLs from your templates appear in two places:
+
+1. **Apify Console**: In the Output tab of your Actor run
+2. **API Response**: In the `output` property when calling the GET Run endpoint
+
+The examples below demonstrate various template patterns and their results in both the Console and API.
+
 ## Examples
 
 ### Linking default dataset