Updated release notes to include two latest PRs.
Updated release notes to include two latest PRs.

bhermanmit/openmc,johnnyliu27/openmc,paulromano/openmc,johnnyliu27/openmc,mit-crpg/openmc,nhorelik/openmc,liangjg/openmc,johnnyliu27/openmc,amandalund/openmc,johnnyliu27/openmc,walshjon/openmc,shikhar413/openmc,liangjg/openmc,samuelshaner/openmc,wbinventor/openmc,shikhar413/openmc,shenqicang/openmc,liangjg/openmc,bhermanmit/openmc,walshjon/openmc,mit-crpg/openmc,smharper/openmc,wbinventor/openmc,wbinventor/openmc,nhorelik/openmc,sxds/opemmc,lilulu/openmc,shikhar413/openmc,shikhar413/openmc,samuelshaner/openmc,smharper/openmc,samuelshaner/openmc,wbinventor/openmc,paulromano/openmc,sxds/opemmc,walshjon/openmc,lilulu/openmc,amandalund/openmc,shenqicang/openmc,liangjg/openmc,paulromano/openmc,samuelshaner/openmc,amandalund/openmc,amandalund/openmc,lilulu/openmc,smharper/openmc,kellyrowland/openmc,mit-crpg/openmc,walshjon/openmc,mjlong/openmc,kellyrowland/openmc,paulromano/openmc,mit-crpg/openmc,mjlong/openmc,smharper/openmc