gnu: Add emacs-rail.

* gnu/packages/emacs-xyz.scm (emacs-rail): New variable.

gnu/packages/emacs-xyz.scm

@@ -15518,6 +15518,27 @@ (define-public emacs-monroe
 distribution, primarily targeting Clojure users")
     (license license:gpl3+)))
 
+(define-public emacs-rail
+  (package
+    (name "emacs-rail")
+    (version "0.4.0")
+    (source
+     (origin
+       (method git-fetch)
+       (uri (git-reference
+             (url "https://github.com/Sasanidas/Rail")
+             (commit version)))
+       (file-name (git-file-name name version))
+       (sha256
+        (base32 "1i07zv0z6r46jpg22x99a1izyfp6536xf951ibyr9kis5bql5jz9"))))
+    (build-system emacs-build-system)
+    (home-page "https://github.com/Sasanidas/Rail")
+    (synopsis "Generic nREPL client for Emacs")
+    (description
+     "Rail is a nREPL client based on monroe with similar features, but aims
+to be a more complete implementation.")
+    (license license:gpl3+)))
+
 (define-public emacs-orgalist
   (package
     (name "emacs-orgalist")