Document file types this works on

README.rst

@@ -44,12 +44,43 @@ Usage example
    # This will modify the README.md file in place
    $ doccmd --language=go --command="gofmt -w" README.md
 
+What does it work on?
+---------------------
+
+* reStructuredText (`.rst`)
+
+.. code-block:: rst
+
+   .. code-block:: shell
+
+      echo "Hello, world!"
+
+* Markdown (`.md`)
+
+.. code-block:: markdown
+
+   ```shell
+   echo "Hello, world!"
+   ```
+
+* MyST (`.md` with MyST syntax)
+
+.. code-block:: markdown
+
+   ```{code-block} shell
+   echo "Hello, world!"
+   ```
+
+* Want more? Open an issue!
+
 TODO:
 
 * Add documentation (automated, and link to it, and add pre-commits for Sphinx stuff, update urls.Source)
 * Release pre-commit hook
 * Verbose mode... "Running command "X" against README.rst example from line ..."
 * Option to not delete file
+* Document https://sybil.readthedocs.io/en/latest/rest.html#skipping-examples on docrun, and make it work
+* https://github.com/simplistix/sybil/blob/master/sybil/parsers/rest/codeblock.py add .. code (not just code block), and same for MyST where it is even more popular
 
 .. |Build Status| image:: https://github.com/adamtheturtle/doccmd/actions/workflows/ci.yml/badge.svg?branch=main
    :target: https://github.com/adamtheturtle/doccmd/actions