Drop inline callouts from docs

[nik9000]

We're working to switch the core of the docs build tools from the no-longer-maintained AsciiDoc to the actively-maintained Asciidoctor. For the most part Asciidoctor is compatible with AsciiDoc or we've made it compatible with extensions. But in one case we've decided not to make it compatible because it is both difficult and doesn't make the docs a lot better. It does require that we change a bunch of asciidoc files, sadly. In particular, we need to drop "inline callouts". An example from elasticsearch-hadoop:

.Map/Reduce
["source","xml",subs="attributes"]
----
<dependency>
  <groupId>org.elasticsearch</groupId>
  <artifactId>elasticsearch-hadoop-mr<1></artifactId>
  <version>{ver}</version>
</dependency>
----

<1> 'mr' artifact

It can be made to be supported with:

.Map/Reduce
["source","xml",subs="attributes"]
----
<dependency>
  <groupId>org.elasticsearch</groupId>
  <artifactId>elasticsearch-hadoop-mr</artifactId> <1>
  <version>{ver}</version>
</dependency>
----

<1> 'mr' artifact