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

- replace tabs with spaces where possible
- remove line ending spaces
- remove double/triple newlines at EOF
- fix a non-UTF-8 character
- cleanup a few indentations/line continuations
  in manual examples

Closes https://github.com/curl/curl/pull/3037

We're mostly saying just "curl" in lower case these days so here's a big
cleanup to adapt to this reality. A few instances are left as the
project could still formally be considered called cURL.

Renamed the CURLX_ONES file list definition in order to a) try and be
consistent with other file lists and b) to allow for the addition of
the curlx header files, which will assist with Visual Studio project
files generation rather than hard coding those files.

This is similar to how it's done in the lib directory.
The Amiga build appears to have been broken for a year because
of a missing homedir.c

in the Watcom makefiles aren't quite correct).