correct bad information about license notice in source files
correct bad information about license notice in source files

https://www.gnu.org/licenses/identify-licenses-clearly.html:
"I did not know how developers would respond to this innovation, so I
decided to give each developer a choice about allowing future
versions. This meant developers could release a program under GNU GPL
version 1 only, or release it under GPL version 1 or any later
version. The way developers state their choice is in the license notice
that goes at the start of each source file. That's where the GPL says
the decision is stated."

https://spdx.org/using-spdx#identifiers:
"The SPDX Work-group proposes to use SPDX license identifiers to
indicate the license at the file level."

pchaigno/licensee,benbalter/licensee,benbalter/licensee,pchaigno/licensee