zsh: add fr function

modules/home/common/fr.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+# find and replace strings with rg
+# Usage: fr OLD NEW
+
+fr() {
+  rg -lF "$1" | xargs sed -i "s|$1|$2|g"
+}

modules/home/common/zsh.nix

@@ -12,6 +12,7 @@ in
       PROMPT='%F{green}%n%f@%F{blue}%m%f %B%1~%b > '
       RPROMPT='[%F{yellow}%?%f]'
     ''
-    + builtins.readFile ./cdf.sh;
+    + builtins.readFile ./cdf.sh
+    + builtins.readFile ./fr.sh;
   };
 }