chore: update siyuan category in service templates

Update generated service template JSON files to reflect the category
field added to siyuan.yaml (documentation category).

templates/service-templates-latest.json

@@ -3791,7 +3791,7 @@
             "markdown",
             "pkm"
         ],
-        "category": null,
+        "category": "documentation",
         "logo": "svgs/siyuan.svg",
         "minversion": "0.0.0",
         "port": "6806"

templates/service-templates.json

@@ -3791,7 +3791,7 @@
             "markdown",
             "pkm"
         ],
-        "category": null,
+        "category": "documentation",
         "logo": "svgs/siyuan.svg",
         "minversion": "0.0.0",
         "port": "6806"