observers are not part of ActiveModel [ci skip]
Typo fix [ci skip]

Fixing the typo which is formed a not required link.  Check
here http://api.rubyonrails.org/classes/ActionController/Base.html
under paramters section
keeping it under tt tag

gets reverted here ec8ef1e1055c4e1598da13f49d30261f07f4a9b4
Using flat_map instead of map and flatten

original commit 8998441967a8cfc6e4302c29664ab9d0acd77704

Reverted here ec8ef1e1055c4e1598da13f49d30261f07f4a9b4
Minor align BR tags with HTML void - with reference to the generators code change - https://github.com/rails/rails/commit/f038d4cc5fe1ac21f92c7e32c61ff85a0c816f3f
Added ActionView in rake about [ci skip]
Merge pull request #12481 from arunagw/fixes

Few fixes which includes revert fixes