Add Bash completion for show-release-notes command

The completion will provide correct suggestions for all 3 arguments.

completions/git-elegant.bash

@@ -1,27 +1,46 @@
 #!/usr/bin/env bash
 
 _git_elegant() {
-    local cur prev opts
     COMPREPLY=()
-    cur="${COMP_WORDS[COMP_CWORD]}"
-    prev="${COMP_WORDS[COMP_CWORD-1]}"
+    local cursor="${COMP_WORDS[COMP_CWORD]}"
 
-    case "${prev}" in
+    # the first word prior to the ${cursor}
+    case ""${COMP_WORDS[COMP_CWORD-1]}"" in
         elegant|git-elegant)
-            opts=($(git elegant commands))
-            COMPREPLY=( $(compgen -W "${opts[*]}" -- ${cur}) )
+            local opts=($(git elegant commands))
+            COMPREPLY=( $(compgen -W "${opts[*]}" -- ${cursor}) )
             return 0 ;;
         pull|epull)
             local data=$(git branch | awk -F ' +' '! /\(no branch\)/ {print $2}')
-            COMPREPLY=( $(compgen -W "${data}" ${cur}) )
+            COMPREPLY=( $(compgen -W "${data}" ${cursor}) )
             return 0 ;;
         accept-work|obtain-work)
             COMPREPLY=(
-                $(compgen -W "$(git branch --remotes --list)" -- ${cur})
+                $(compgen -W "$(git branch --remotes --list)" -- ${cursor})
             )
             return 0 ;;
-        *)
+        show-release-notes)
+            COMPREPLY=( $(compgen -W "simple smart" ${cursor}) )
             return 0 ;;
+        *)  ;;
+    esac
+
+    # the second word prior to the ${cursor}
+    case "${COMP_WORDS[COMP_CWORD-2]}" in
+        show-release-notes)
+            local opts=($(git for-each-ref --sort "-version:refname" --format "%(refname:short)" refs/**))
+            COMPREPLY=( $(compgen -W "${opts[*]}" -- ${cursor}) )
+            return 0 ;;
+        *)  ;;
+    esac
+
+    # the third word prior to the ${cursor}
+    case "${COMP_WORDS[COMP_CWORD-3]}" in
+        show-release-notes)
+            local opts=($(git for-each-ref --sort "-version:refname" --format "%(refname:short)" refs/**))
+            COMPREPLY=( $(compgen -W "${opts[*]}" -- ${cursor}) )
+            return 0 ;;
+        *)  ;;
     esac
 }