man: make tilde and caret characters to render correctly

man: make tilde and caret characters to render correctly

As mentioned in 'Generating optimal glyphs' title in the manual page
mentioned in reference:

    Where a proper caret (^) that renders well in both a terminal and PDF is
    required, use "\(ha".

    Using a naked "~" character results in a poor rendering in PDF.  Instead
    use "\(ti".

Reference: https://man7.org/linux/man-pages/man7/man-pages.7.html#STYLE_GUIDE
Signed-off-by: Sami Kerola <kerolasa@iki.fi>