Add a .github/README.md

This is based on the existing README and is an almost exact copy.
Some minor formatting changes to improve the rendering but the text
remains the same. This is done because not having a formatted README
is blocking some other changes.[^1]

t/porting/copyright.t was also adjusted to check the copyright in
.github/README.md

*Long term*: In the long term the contents of README and .github/README.md
will differ. Since these serve a different purpose:
- README: this is included with each release and for that it's more then
  good enough enough;
- .github/README.md: this is for people viewing the repository on GitHub
  and for that the current README is - in my opinion - not good enough.
  It should be much more informative (compare it with some other repos
  and that should be obvious, in #18965 there are some examples but
  many more exist).

[^1]: rendering platform specific READMEs as POD in GitHub.

1 files changed, 128 insertions, 0 deletions

diff --git a/.github/README.md b/.github/README.md
new file mode 100644
index 0000000000..79aafc8549
--- /dev/null
+++ b/.github/README.md
@@ -0,0 +1,128 @@
+```
+Perl is Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
+2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012,
+2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022
+by Larry Wall and others.
+All rights reserved.
+```
+
+# ABOUT PERL
+
+Perl is a general-purpose programming language originally developed for
+text manipulation and now used for a wide range of tasks including
+system administration, web development, network programming, GUI
+development, and more.
+
+The language is intended to be practical (easy to use, efficient,
+complete) rather than beautiful (tiny, elegant, minimal).  Its major
+features are that it's easy to use, supports both procedural and
+object-oriented (OO) programming, has powerful built-in support for text
+processing, and has one of the world's most impressive collections of
+third-party modules.
+
+For an introduction to the language's features, see pod/perlintro.pod.
+
+For a discussion of the important changes in this release, see
+pod/perldelta.pod.
+
+There are also many Perl books available, covering a wide variety of topics,
+from various publishers.  See pod/perlbook.pod for more information.
+
+
+# INSTALLATION
+
+If you're using a relatively modern operating system and want to
+install this version of Perl locally, run the following commands:
+
+    ./Configure -des -Dprefix=$HOME/localperl
+    make test
+    make install
+
+This will configure and compile perl for your platform, run the regression
+tests, and install perl in a subdirectory "localperl" of your home directory.
+
+If you run into any trouble whatsoever or you need to install a customized
+version of Perl, you should read the detailed instructions in the "INSTALL"
+file that came with this distribution.  Additionally, there are a number of
+"README" files with hints and tips about building and using Perl on a wide
+variety of platforms, some more common than others.
+
+Once you have Perl installed, a wealth of documentation is available to you
+through the 'perldoc' tool.  To get started, run this command:
+
+    perldoc perl
+
+
+# IF YOU RUN INTO TROUBLE
+
+Perl is a large and complex system that's used for everything from
+knitting to rocket science.  If you run into trouble, it's quite
+likely that someone else has already solved the problem you're
+facing. Once you've exhausted the documentation, please report bugs to us
+at the GitHub issue tracker at https://github.com/Perl/perl5/issues
+
+While it was current when we made it available, Perl is constantly evolving
+and there may be a more recent version that fixes bugs you've run into or
+adds new features that you might find useful.
+
+You can always find the latest version of perl on a CPAN (Comprehensive Perl
+Archive Network) site near you at https://www.cpan.org/src/
+
+If you want to submit a simple patch to the perl source, see the "SUPER
+QUICK PATCH GUIDE" in pod/perlhack.pod.
+
+Just a personal note:  I want you to know that I create nice things like this
+because it pleases the Author of my story.  If this bothers you, then your
+notion of Authorship needs some revision.  But you can use perl anyway. :-)
+
+The author.
+
+
+# LICENSING
+
+```
+This program is free software; you can redistribute it and/or modify
+it under the terms of either:
+
+	a) the GNU General Public License as published by the Free
+	Software Foundation; either version 1, or (at your option) any
+	later version, or
+
+	b) the "Artistic License" which comes with this Kit.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See either
+the GNU General Public License or the Artistic License for more details.
+
+You should have received a copy of the Artistic License with this
+Kit, in the file named "Artistic".  If not, I'll be glad to provide one.
+
+You should also have received a copy of the GNU General Public License
+along with this program in the file named "Copying". If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+Boston, MA 02110-1301, USA or visit their web page on the internet at
+https://www.gnu.org/copyleft/gpl.html.
+
+For those of you that choose to use the GNU General Public License,
+my interpretation of the GNU General Public License is that no Perl
+script falls under the terms of the GPL unless you explicitly put
+said script under the terms of the GPL yourself.  Furthermore, any
+object code linked with perl does not automatically fall under the
+terms of the GPL, provided such object code only adds definitions
+of subroutines and variables, and does not otherwise impair the
+resulting interpreter from executing any standard Perl script.  I
+consider linking in C subroutines in this manner to be the moral
+equivalent of defining subroutines in the Perl language itself.  You
+may sell such an object file as proprietary provided that you provide
+or offer to provide the Perl source, as specified by the GNU General
+Public License.  (This is merely an alternate way of specifying input
+to the program.)  You may also sell a binary produced by the dumping of
+a running Perl script that belongs to you, provided that you provide or
+offer to provide the Perl source as specified by the GPL.  (The
+fact that a Perl interpreter and your code are in the same binary file
+is, in this case, a form of mere aggregation.)  This is my interpretation
+of the GPL.  If you still have concerns or difficulties understanding
+my intent, feel free to contact me.  Of course, the Artistic License
+spells all this out for your protection, so you may prefer to use that.
+```