ftp/wget: Tweak docs options
- Add a separate option to control whether man page is to be installed
- Handle wgetrc.sample with @sample, according to https://www.freebsd.org/doc/en/books/porters-handbook/plist-config.html and https://www.freebsd.org/doc/en/books/porters-handbook/plist-keywords.html#plist-keywords-sample
- Now the DOCS option only controls whether an info page is installed or not
Submitted by: jkim