Two small fixes in installation instructions.
Two small fixes in installation instructions.

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