Relax list-indentation requirements of 'showdown' for Changelog/History.
Relax list-indentation requirements of 'showdown' for Changelog/History.

The pre-1.5.0 state more closely mimicked GitHub markdown flavor, which
is what we use for `History.md` and is being parsed here.

Hansoft/meteor,Hansoft/meteor,Hansoft/meteor,Hansoft/meteor,Hansoft/meteor,Hansoft/meteor,Hansoft/meteor