Expand Chain.reduce docstring: methodology and return
Expand Chain.reduce docstring: methodology and return

The methodology is explained through a simple example mostly
borrowed from the chain_simple.xml test chain. A few different
cases are presented, showing the effect of initial isotopes and
search depth.

A description of the returned chain is also included.

mit-crpg/openmc,liangjg/openmc,paulromano/openmc,walshjon/openmc,amandalund/openmc,mit-crpg/openmc,smharper/openmc,walshjon/openmc,paulromano/openmc,paulromano/openmc,shikhar413/openmc,shikhar413/openmc,amandalund/openmc,shikhar413/openmc,mit-crpg/openmc,smharper/openmc,amandalund/openmc,walshjon/openmc,liangjg/openmc,smharper/openmc,amandalund/openmc,paulromano/openmc,shikhar413/openmc,walshjon/openmc,smharper/openmc,liangjg/openmc,mit-crpg/openmc,liangjg/openmc