[tldoc] png files and html

[Karl Berry]

    I've just noticed that .png files cannot be found by texlive-xx.html
    in the texlive-doc/doc/<lang> area. So I have to copy .png (~90kb)
    also to polish/texlive-pl/
    Does it hurt so much if we have some redundance? 

Yes, those png files need to exist in each doc dir.  I've been adding
them as needed when I remember.  I'll double-check them all.

Siep and I could not think of any better solution.