Coloring part of an article

[Olivier Sirven]

Hello,

I often receive diff patches by email and I saw gnus sometimes colorize
part of the article buffer when there is some lisp code or even diff
text.

I checked the manual but the only relevant part I found is to add my own
functions to gnus-part-display-hook hook. But as this behavior already
exist in some case, I'm pretty sure there is some pattern to declare so
gnus knows how and when to colorize a buffer.

Any advice would be welcome ;)

Thanks

Olivier