Introducing the curl bug bounty program on hackerone. We now recommend
filing security issues directly in the hackerone ticket system which
only is readable to curl security team members.
Assisted-by: Daniel Gustafsson
Closes#3488
Use proper Markdown hyperlink format for the Bountygraph links in order
for the generated website page to be more user friendly. Also link to
the sponsors to give them a little extra credit.
Closes#3082
Reviewed-by: Daniel Stenberg <daniel@haxx.se>
