Fixed missing code block in installation docs
Fixed missing code block in installation docs

mrshirts/pymbar,choderalab/pymbar,wesbarnett/pymbar,mrshirts/pymbar,jchodera/pymbar,Lnaden/pymbar,jchodera/pymbar,choderalab/pymbar,wesbarnett/pymbar,mrshirts/pymbar,kyleabeauchamp/pymbar,kyleabeauchamp/pymbar,choderalab/pymbar,Lnaden/pymbar,wesbarnett/pymbar,mrshirts/pymbar,jchodera/pymbar,kyleabeauchamp/pymbar,Lnaden/pymbar,wesbarnett/pymbar,kyleabeauchamp/pymbar,jchodera/pymbar