remove leftover if after deprecation removal (68563128).
Removed redundant upgrade docs on new cookies.

[ci skip]
Merge pull request #11261 from ryan-endacott/fixguide

Removed redundant upgrade docs on new cookies.
Replaced older rocket sign to new :
Merge pull request #11295 from ankit8898/master

Replaced older rocket sign to new  ":"
SQL Keywords to be in UPPERCASE
Merge pull request #11297 from ankit8898/master

SQL keywords in UPPERCASE
Removed deprecated `Rails.application.railties.engines`.
Merge pull request #11300 from arunagw/railties-engine-deprecation-removed

Removed deprecated `Rails.application.railties.engines`.