Add list of bridge chapters with details

This is a work in progress: the actual list expected has one line
for each end of a pair of bridge chapters, with the type 'Chapter 1'
for the left part and 'Chapter 2' for the right part of the pair.
Complete the list of bridge chapters in expected format

This is a union of the occurrences of chapters on the left
of a pair (Type: 'Chapter 1') and chapters on the right of
a pair (Type: 'Chapter 2').