Reported by the new script 'scripts/copyright.pl'. The script has a
regex whitelist for the files that don't need copyright headers.
Removed three (mostly usesless) README files from docs/
Closes#5141
The CURLOPT_COOKIE doc says it "sets the cookie header explicitly in the
outgoing request(s)." However there seems to be some user confusion
about cookie modification. Document that the cookies set by this option
are not modified by the cookie engine.
Bug: http://curl.haxx.se/mail/lib-2015-05/0115.html
Reported-by: Alexander Dyagilev