🤖 chore(.gitignore): Add leading slash to ignored gh-pages directory.

These changes were automatically generated by a transform whose code can be found at:
  - https://github.com/aureooms/rejuvenate/blob/c49b495bb7cf0f1290b0f09fc31eab036a3409b2/src/transforms/gitignore:fix-gh-pages.js
Please contact the author of the transform if you believe there was an error.

Author: a-flying-potato

.gitignore

@@ -13,4 +13,4 @@ jspm_packages
 .nyc_output
 
 # Documentation
-gh-pages
+/gh-pages