anchor.diff:  when looking at an ssh terminal, need compact and aligned text.  The
   cat API aims to meet this need.
   
  -All the cat commands accept a query string parameter `h` to see all
  -the headers and info they provide, and the `/_cat?h` command lists all
  +All the cat commands accept a query string parameter `help` to see all
  +the headers and info they provide, and the `/_cat?help` command lists all
   the available commands.
   
   [float]
  
positive.code: [[help]]
  === Help
  
  Each of the commands accepts a query string parameter `h` which will
  output its available columns.
  
  [source,shell]
  --------------------------------------------------
  % curl 'localhost:9200/_cat/master?h'
  id   | node id
  ip   | node transport ip address
  node | node name
  
negative.code: [[headers]]
  === Headers
  
  Each of the commands accepts a query string parameter `h` which forces
  only those columns to appear.
  
  [source,shell]
  --------------------------------------------------
  % curl 'n1:9200/_cat/nodes?h=ip,port,heapPercent,name'
  192.168.56.40 9300 40.3 Captain Universe
  192.168.56.20 9300 15.3 Kaluu
  192.168.56.50 9300 17.0 Yellowjacket
  