$output: ParserOutput that is produced from the page
$engine: SearchEngine for which the indexing is intended
+'SearchResultsAugment': Allows extension to add its code to the list of search
+result augmentors.
+&$setAugmentors: List of whole-set augmentor objects, must implement ResultSetAugmentor
+&$rowAugmentors: List of per-row augmentor objects, must implement ResultAugmentor.
+Note that lists should be in the format name => object and the names in both lists should
+be distinct.
+
'SecondaryDataUpdates': Allows modification of the list of DataUpdates to
perform when page content is modified. Currently called by
AbstractContent::getSecondaryDataUpdates.