Add licensing and copyright information for all files in this repository. This
either happens in the file itself as a comment header or in the file
`.reuse/dep5`.
This commit also adds a Github workflow to check pull requests and adapts
copyright.pl to the changes.
Closes#8869
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
This makes it easier for emacs users to automatically get the right
2-space indentation when they edit curl source files.
c++-mode is in there as well because Emacs can't easily know if
something is a C or C++ header.
Closes#574
