x11/sterm: Update to 0.8

• Fix LICENSE and set it to MIT
• Fix the way we handle the terminfo of x11/sterm. FreeBSD 12, 11-STABLE, and 11.2-RELEASE do not require any additional configuration (thanks to bapt@) [1]. For older versions, there is a simple set of instructions on how to configure terminfo for x11/sterm in pkg-message.
• Create a symbolic link to user-defined config.h instead of making a copy as is done in other suckless.org ports such as x11-wm/dwm and www/quark.
• Respect CPPFLAGS
• Add some files to DOCS and DATA
• Eliminate an unnecessary .for loop during install
• Use HTTPS in WWW
• Add UPDATING entry as old config.h files will need to be updated for the newer version

[1] https://svnweb.freebsd.org/changeset/base/331006

Changes: https://git.suckless.org/st/log/?qt=range&q=0.7..0.8
PR: 226632
Submitted by: 0mp
Approved by: Piotr Kubaj <pkubaj@anongoth.pl> (maintainer)