Fix a typo in Rails layout comments

Signed-off-by: Takuya Noguchi <takninnovationresearch@gmail.com>

app/views/layouts/_head.html.haml

 - page_description brand_title unless page_description
 
--# Needs a redirect on the client side since it's using an anchor to distuingish
+-# Needs a redirect on the client side since it's using an anchor to distinguish
 -# between sign in and registration. We need to inline the JS to not render
 -# anything from this page beforehand.
 -# Part of an experiment to build a new sign up flow. Will be removed again with