the documentation generator now supports ':test:' for the testing of test snippets

changelog.md

@@ -98,3 +98,10 @@ This now needs to be written as:
 - Added ``system.runnableExamples`` to make examples in Nim's documentation easier
   to write and test. The examples are tested as the last step of
   ``nim doc``.
+- Nim's ``rst2html`` command now supports the testing of code snippets via an RST
+  extension that we called ``:test:``::
+
+    .. code-block:: nim
+        :test:
+      # shows how the 'if' statement works
+      if true: echo "yes"