RFR: 8184023: Fix tables in doc comments to be accessible

[Jonathan Gibbons]

Please review the following fix to the doc comments in the langtools repo.

The primary goal is to fix user-written tables in doc comments for 
accessibility,
either by updating tables to use scope=row|col in header cells for 
simple tables,
or by using the headings attribute on data cells in more complex tables.

In this case, there are just two tables that need to be updated. The first
has complex headers and needs to be updated manually.  The second can
be converted to a table with class="striped" and then updated automatically
by a small temporary Java utility.

In addition, now that we have a unified docs bundle, the entries in the 
second column
can be linked to the corresponding doc pages. Doing so revealed two 
errors in the
content of the table, which have also been fixed (using Type instead of 
TypeMirror.)

There are a couple of minor style changes as well, to use {@code } 
around option names.

JBS: https://bugs.openjdk.java.net/browse/JDK-8184023
Webrev: http://cr.openjdk.java.net/~jjg/8184023/webrev.00/

-- Jon