Fix docs-push-gh-pages

Author: reo7sp

tools/docs-push-gh-pages

@@ -3,7 +3,7 @@ set -e
 
 ./docs-generate
 cd ..
-git checkout gh-pages
+git checkout --track origin/gh-pages
 find . -maxdepth 1 -not -name "docs" -not -name ".git" -not -name "tools" -print0 | xargs -0 rm -r || true
 mv docs/* .
 mv docs/.nojekyll .