RFR: JDK-8215131 Pandoc 2.3/build documentation fixes

[Magnus Ihse Bursie]

It turned out pandoc 2.3 has "smart quotes" handling which is somewhat 
broken. Turn it off.

Also, when regenerating build documentation it turned out that some 
table columns were incorrectly formatted in markdown which made them 
lose their alignment.

Bug: https://bugs.openjdk.java.net/browse/JDK-8215131
WebRev: 
http://cr.openjdk.java.net/~ihse/JDK-8215131-pandoc-2-no-smart-quotes/webrev.01

/Magnus