Updating/adding some docstrings.
Updating/adding some docstrings.

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