docs: Reframe Supported Tools

We don't want make it sound like we don't support any doc tool,
but these are just some of the popular ones.

I think this framing works well.

docs/user/intro/doctools.rst

@@ -1,11 +1,16 @@
-Supported tools
-===============
+Popular Documentation Tools
+===========================
 
-Read the Docs provides hosting for static html documentation generated by Sphinx,
-MkDocs, Docusaurus and a variety of other tools.
+Read the Docs provides documentation hosting for any tool that can output HTML.
+We provide a number of features on top of that that is well-suited to documentation specifically,
+but you can host any kind of HTML content on Read the Docs.
 
-Here are minimal configuration examples for some common tools,
-with more coming soon.
+Below is a list of popular documentation tools that you can use to write your documentation.
+
+.. seealso::
+
+   :doc:`/build-customization`
+   Learn how to build documentation with any tool.
 
 .. grid:: 2