Add pandoc doc

docs/content/en/content-management/formats.md

@@ -51,7 +51,7 @@ Hugo passes reasonable default arguments to these external helpers by default:
 
 - `asciidoctor`: `--no-header-footer -`
 - `rst2html`: `--leave-comments --initial-header-level=2`
-- `pandoc`: `--mathjax`
+- `pandoc`: `--mathjax --toc -s --quiet`
 
 {{% warning "Performance of External Helpers" %}}
 Because additional formats are external commands, generation performance will rely heavily on the performance of the external tool you are using. As this feature is still in its infancy, feedback is welcome.
@@ -120,6 +120,12 @@ parameters. Run Hugo with `-v`. You will get an output like
 INFO 2019/12/22 09:08:48 Rendering book-as-pdf.adoc with C:\Ruby26-x64\bin\asciidoctor.bat using asciidoc args [--no-header-footer -r asciidoctor-html5s -b html5s -r asciidoctor-diagram --base-dir D:\prototypes\hugo_asciidoc_ddd\docs -a outdir=D:\prototypes\hugo_asciidoc_ddd\build -] ...
 ```
 
+### External Helper pandoc
+preserveTOC
+: By default, Hugo removes the table of contents generated by pandoc and provides it through the built-in variable [`.TableOfContents`](/content-management/toc/) to enable further customization and better integration with the various Hugo themes. This option can be set to `true` to preserve pandoc's TOC in the generated page.
+
+{{< code-toggle config="markup.pandoc" />}}
+
 ## Learn Markdown
 
 Markdown syntax is simple enough to learn in a single sitting. The following are excellent resources to get you up and running:

docs/data/docs.json

@@ -1668,6 +1668,9 @@
         "failureLevel": "fatal",
         "workingFolderCurrent": false,
         "preserveTOC": false
+      },
+      "pandoc": {
+        "preserveTOC": false
       }
     },
     "mergeStrategy": {