Address the presence of multiple and different versions of the rename command
as discussed in issue #3125.
Changes made:
- Moved common/rename.md to linux/prename.md, documenting the Debian
Perl rename command (which is deprecated).
- Created linux/file-rename.md for the Debian/Ubuntu `file-rename`.
- Created linux/perl-rename.md with examples for Arch Linux `perl-rename`.
- Created linux/rename.md for the `rename` command offered by the the
`util-linux` package, the most common one and supported by the most
platforms.
