Rename distributed PDFs in doc folder

The names should be more expressive. For example, dynare.pdf should be Adjemian_et_al_2011_Dynare_Manual_4.pdf or similar.

@svillemot As you are working on the build system, could you please also do this?

I'm not entirely convinced by your suggestion. It is rather usual to name a reference manual after the name of the software. Maybe dynare-manual.pdf ?

That would be fine with me. The goal is to have the files more expressively named.

closed via commit e5f938a8