RFR: JDK-8185740: The help-doc.html generated by the doclet is outdated

[Jonathan Gibbons]

Please review a simple fix for JDK 11 to update the contents of the 
generated Help page
in a docs bundle. Text has been added for Modules and Search, some obsolete
items have been removed, and there are some minor editorial tweaks to 
improve
the text in various places.

Although a test was affected/updated, there are no explicit regression tests
for this work: it is a combination of noreg-doc, noreg-hard, noreg-other.

JBS: https://bugs.openjdk.java.net/browse/JDK-8185740
Webrev: http://cr.openjdk.java.net/~jjg/8185740/webrev.00/
JDK API: http://cr.openjdk.java.net/~jjg/8185740/api.00/

-- Jon