various: update copyright year
treeb4c0473dfa3fc0a2f7e4c13cbee3031855dd8d77
-rw-r--r-- 1526 LICENSE
-rwxr-xr-x 144416 Markdown.pl
lrwxrwxrwx 11 Markdown.pm -> Markdown.pl
-rw-r--r-- 15933 README
lrwxrwxrwx 6 README.md -> README
-rw-r--r-- 9672 basics.md
-rw-r--r-- 49719 syntax.md