Remove unused line
[ci skip] Change three backticks to just one
Merge pull request #18069 from yui-knk/fix/guide

[ci skip] Change three backticks to just one
Merge pull request #18068 from kamipo/remove_unused_line

Remove unused line
Add _mailer suffix to generated file names.

It is somewhat confusing that controllers and jobs follow
this convention, but mailers do not.