[tldoc] http vs https text string links on the manual

[Karl Berry]

    I'm just wondering if all hyperlinks instances of pdftex on the manual
    shouldn't have say https://tug.org/applications/pdftex rather than
    http://pdftex.org

Hi Carlos - I don't want to change this, but if you want to change it in
your translation, feel free.

As I wrote before, I prefer to use the most future-proof urls
available. It is conceivable that pdftex.org will not always redirect to
tug.org. I view http vs. https as secondary to this. I realize that
opinions differ. -k