Allow publishing of folders starting with `_`
GitHub pages uses Jekyll by default. Jekyll ignores all files and
folders beginning with `_`. Sphinx is hard-coded to always output its
theme to a folder named `_static`. In order to include `_static` in the
published site, add a `.nojekyll` file to disable Jekyll processing (we
don't need it, as we have html files and nothing needing Jekyll
processing like markdown).
diff --git a/docs/.nojekyll b/docs/.nojekyll
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/docs/.nojekyll