Merge pull request #284577 from laujan/288060-add-catetory-as-optional-param

update sync doc optional param

Author: prmerger-automator[bot]

articles/ai-services/translator/document-translation/reference/translate-document.md

@@ -67,6 +67,7 @@ Query string parameters:
 |**sourceLanguage**|Specifies the language of the input document. If the `sourceLanguage` parameter isn't specified, automatic language detection is applied to determine the source language.|
 |&bull; **glossary=**<br> &bull; **type=**|&bull; Path to the file location for your custom glossary and file format type.</br> &bull; Ex:**"glossary=@D:\Test\SDT\test-simple-glossary.csv;type=text/csv**|
 |**allowFallback**|&bull; A boolean specifying that the service is allowed to fall back to a `generalnn` system when a custom system doesn't exist. Possible values are: `true` (default) or `false`. <br>&bull; `allowFallback=false` specifies that the translation should only use systems trained for the category specified  by the request.<br>&bull; If no system is found with the specific category, the request returns a 400 status code. <br>&bull; `allowFallback=true` specifies that the service is allowed to fall back to a `generalnn` system when a custom system doesn't exist.|
+|**category**|A string specifying the category (domain) for the translation. This parameter is used to get translations from a customized system built with [Custom Translator](../../custom-translator/how-to/translate-with-custom-model.md#how-to-translate). To use your deployed customized system for synchronous document translation, add the `Category ID` from your Custom Translator project details to the `category` parameter. The default value is: `generalnn`.|
 
 ### Request Body