Follow XDG Base Directory Specification

[NI57721]

[NI57721]

There are four files made just under $HOME.

• ~/.pki
  There is a patch for this, but somehow it is not merged.
  https://bugs.chromium.org/p/chromium/issues/detail?id=1038587
• ~/.wget-hsts
  Somehow, wget has come to stop creating ~/.wget-hsts
  https://lists.gnu.org/archive/html/bug-wget/2017-03/msg00053.html
• ~/.fzf.bash, ~/.bashrc
  https://github.com/junegunn/fzf/issues/1277