content/presentation-mode: Fix presentation mode links

- MyST mixes document, ref, and HTML links in the same syntax, so this
  can't be forced to be a HTML link, so it tries to parse it as a
  semantic internal link, fails, and breaks the build.
- Temporary workaround: tell it to evaluate it as ReST and leave it as
  it was.

content/presentation-mode.md

@@ -33,5 +33,7 @@ In presentation mode:
 
 Examples:
 
-- [View this page as an example of minipres](../sample-episode-rst/?minipres).
-- [View this page in "plain" mode](../sample-episode-rst/?plain).
+```{eval-rst}
+- `View this page as an example of minipres <../sample-episode-rst/?minipres>`__.
+- `View this page in "plain" mode <../sample-episode-rst/?plain>`__.
+```