[pdftex] Problems finding installation version of pdftex on windows

[Han The Thanh]

If you are using windows, why not to install fptex or miktex? It's much
easier. There are many things that are needed to setup to run pdftex, and
distributions like tetex, fptex or miktex simplifies much our life.

The instructions in the manual are out-of-date. I should have updated it,
but couldn't find time to do it.

Thanh