Add clarification note on CompoundModel
Add clarification note on CompoundModel

lpsinger/astropy,pllim/astropy,pllim/astropy,lpsinger/astropy,mhvk/astropy,mhvk/astropy,larrybradley/astropy,mhvk/astropy,lpsinger/astropy,lpsinger/astropy,mhvk/astropy,larrybradley/astropy,pllim/astropy,larrybradley/astropy,astropy/astropy,mhvk/astropy,astropy/astropy,astropy/astropy,larrybradley/astropy,astropy/astropy,pllim/astropy,astropy/astropy,pllim/astropy,larrybradley/astropy,lpsinger/astropy