Move footnotes to /converters.

Signed-off-by: Thomas Hochstein <thh@inter.net>

README.md

@@ -5,14 +5,6 @@ personal use here.
 
 ## Perl
 
-### footnotes.pl
-
-`footnotes` will convert footnotes in MultiMarkDown format
-to the format of the Wordpress plugin
-[footnotes](https://wordpress.org/plugins/footnotes/) and back.
-
-Usage: `footnotes --to mmd|wp [--file $inputfile]`
-
 ### mmm.pl
 
 `mmm` (*MIME multipart/alternative from Markdown*) can
@@ -22,3 +14,12 @@ a Markdown file. Other mail headers (From:, To:, Subject:, ...)
 can be prepended from a template file.
 
 Usage: `mmm [--file $inputfile] [--headers $templatefile]`
+
+### footnotes.pl
+
+`footnotes` will convert footnotes in MultiMarkDown format
+to the format of the Wordpress plugin
+[footnotes](https://wordpress.org/plugins/footnotes/) and back.
+
+Usage: `footnotes --to mmd|wp [--file $inputfile]`
+