fixes for python make.py serve (#2104)

Author: nfearnley

make.py

@@ -62,7 +62,7 @@ def _resolve(p: PathLike, strict: bool = False) -> Path:
 PAPER_SIZE_OPTS['a4'] = ['-D', 'latex_paper_size=a4']
 PAPER_SIZE_OPTS['letter'] = ['-D', 'latex_paper_size=letter']
 ALLSPHINXOPTS       = ['-d', f'{BUILDDIR}/doctrees', *PAPER_SIZE_OPTS[PAPER_SIZE], *SPHINXOPTS, '.']
-SPHINXAUTOBUILDOPTS = ['--watch', './arcade']
+SPHINXAUTOBUILDOPTS = ['--watch', '../arcade', '--ignore', './example_code/how_to_examples/thumbs']
 
 # Important: the i18n builder cannot share the environment and doctrees with the others
 # This allows for internationalization / localization of doc.