diff --git a/.gitignore b/.gitignore
index e91f0cf93..4243988d8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,3 +6,4 @@ coverage/
 .idea
 .sass_cache
 _site
+docs/vendor/
diff --git a/docs/CONTRIBUTING.md b/docs/CONTRIBUTING.md
index 50de9a0d9..b7617b5c6 100644
--- a/docs/CONTRIBUTING.md
+++ b/docs/CONTRIBUTING.md
@@ -22,7 +22,7 @@ cd docs
 gem install bundler
 
 # install all dependencies
-bundle install
+bundle install --path vendor/bundle
 
 # build the site
 bundle exec jekyll serve