Fix issue with newsticker and other included stuff on Lucene webpage [LUCENE-5789]

When talking to asfinfra today, they told me, that there is a solutions for the problem we have on the Lucene web page:

The index markdown file includes other files like the newsticker markdown. If you update the newsticker, the main webpage is not updated, unless you do a fake commit on the index markdown.

The solution is here (Apache Thrift uses this, including example):

```
[18:46] joes4: ThetaPh1: the way to deal with included files is through the %path::dependencies hash
[18:46] ThetaPh1: ah there is a solution for that?
[18:46] joes4: yes see the thrift cms site
[18:46] ThetaPh1: the last time we asked there was only the fake commit on the file that includes
[18:46] ThetaPh1: in short: how must the link look like?
[18:47] joes4: $dependencies{"path_to_base_file"} = [ `@list_of_files_to_be_included` ]
[18:47] joes4: in path.pm
[18:49] ThetaPh1: ok, I'll open a lucene issue to fix this on our website
[18:49] ThetaPh1: it mainly affects news ticker, which is a separte markdown
[18:49] joes4: https://svn.apache.org/repos/asf/thrift/cms-site/trunk/lib/path.pm
[18:49] joes4: they are doing ther state of the art
[18:50] joes4: dynamicly generated %dependencies hash
```

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Migrated from [LUCENE-5789](https://issues.apache.org/jira/browse/LUCENE-5789) by Uwe Schindler (@uschindler), updated Jun 30 2014