The Contextual Help topics can be placed anywhere with the function:
This “topics” are in the /lists/admin/help/ directory, divided by language.
All the content of this /help directory is modified by the public repository:
This Help(“topic”) function print a link in the page, to open a URL like this: /lists/admin/help/?topic=topic
In the Send a Campaign page, this is the Contextual Help for the field Subject:
That is the result of echo the function Help('subject'):
And that Contextual Help, in an english installation, will open the file: /lists/admin/help/en/subject.php.
Or, in a spanish installation, will open the file: /lists/admin/help/es/subject.php.