It's not auto-generated. All by hand (was tedious).
Wow, that's a labor of love. Let's not abandon it, let's use it as a one-time fix to get all the parameter descriptions into HiveConf. Then later we can figure out how to generate hive-default.xml.template from HiveConf for each new release. However there's a problem with the default values, since HiveConf sets them so those are the correct values.
Also, updating would be needed for changes since December 15th. But that's easier once the two files are synchronized.
Hmm ... if HiveConf already has a comment that's different from the description in hive-default.xml.template, should both be kept? Ideally they'd be merged, and sometimes that's an easy edit but other times it requires expert information.
To muddy the waters further, the wiki has some release information and miscellaneous notes that don't have to be merged with HiveConf but shouldn't get lost if we eventually generate the wiki from one of the code files. I've been wanting to go through the list and and fill in the "Added In:" information by grepping the config names in a directory of HiveConf files for all the branches. (Another labor of love, but it's less important than making sure all the parameters are listed in the wiki & hive-default.xml.template.)
Carl Steinbach created the Configuration Properties wikidoc in the first place – how was that done?