rename: address different versions of the command (#3126)

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.

pages/linux/perl-rename.md

@@ -0,0 +1,24 @@
+# rename
+
+> Rename multiple files.
+> NOTE: this page refers to the command from the `perl-rename` Arch Linux package.
+
+- Rename files using a Perl Common Regular Expression (substitute 'foo' with 'bar' wherever found):
+
+`rename {{'s/foo/bar/'}} {{*}}`
+
+- Dry-run - display which renames would occur without performing them:
+
+`rename -n {{'s/foo/bar/'}} {{*}}`
+
+- Force renaming even if the operation would remove existing destination files:
+
+`rename -f {{'s/foo/bar/'}} {{*}}`
+
+- Convert filenames to lower case (use `-f` in case-insensitive filesystems to prevent "already exists" errors):
+
+`rename 'y/A-Z/a-z/' {{*}}`
+
+- Replace whitespace with underscores:
+
+`rename 's/\s+/_/g' {{*}}`