README: Update MELPA badges

Author: minad

README.org

@@ -3,8 +3,8 @@
 #+html: <a href="https://www.gnu.org/software/emacs/"><img alt="GNU Emacs" src="https://github.com/minad/corfu/blob/screenshots/emacs.svg?raw=true"/></a>
 #+html: <a href="https://elpa.nongnu.org/nongnu/gnuplot.html"><img alt="NonGNU ELPA" src="https://elpa.nongnu.org/nongnu/gnuplot.svg"/></a>
 #+html: <a href="https://elpa.nongnu.org/nongnu-devel/gnuplot.html"><img alt="NonGNU-devel ELPA" src="https://elpa.nongnu.org/nongnu-devel/gnuplot.svg"/></a>
-#+html: <a href="https://melpa.org/#/gnuplot"><img alt="MELPA" src="https://melpa.org/packages/gnuplot-badge.svg"/></a>
-#+html: <a href="https://stable.melpa.org/#/gnuplot"><img alt="MELPA Stable" src="https://stable.melpa.org/packages/gnuplot-badge.svg"/></a>
+#+html: <a href="https://releases.melpa.org/#/gnuplot"><img alt="MELPA Releases" src="https://releases.melpa.org/packages/gnuplot-badge.svg"/></a>
+#+html: <a href="https://snapshots.melpa.org/#/gnuplot"><img alt="MELPA Snapshots" src="https://snapshots.melpa.org/packages/gnuplot-badge.svg"/></a>
 
 This package allows running [[http://www.gnuplot.info/][Gnuplot]] files from within the [[https://www.gnu.org/software/emacs/][GNU Emacs]] editor. It
 features:
@@ -20,7 +20,7 @@ above.
 
 * Installation
 
-The easiest way to install =gnuplot= is to directly get it from [[https://elpa.nongnu.org/][ELPA]] or [[https://melpa.org][MELPA]]. You
+The easiest way to install =gnuplot= is to directly get it from [[https://elpa.nongnu.org/nongnu/gnuplot.html][ELPA]] or [[https://releases.melpa.org/#/gnuplot][MELPA]]. You
 should be able to install =gnuplot= by typing
 
 : M-x install-package RET gnuplot RET