completion: Update completion for new bash-it update

Also fix the update completion test

completion/available/bash-it.completion.bash

@@ -87,7 +87,12 @@ _bash-it-comp()
       COMPREPLY=( $(compgen -W "${doctor_args}" -- ${cur}) )
       return 0
       ;;
-    migrate | reload | search | update | version)
+    update)
+      local update_args="stable dev"
+      COMPREPLY=( $(compgen -W "${update_args}" -- ${cur}) )
+      return 0
+      ;;
+    migrate | reload | search | version)
       return 0
       ;;
     enable | disable)

test/completion/bash-it.completion.bats

@@ -58,9 +58,9 @@ function __check_completion () {
   assert_line -n 0 "vagrant vault vim"
 }
 
-@test "completion bash-it: update - show no options" {
+@test "completion bash-it: update - show options" {
   run __check_completion 'bash-it update '
-  assert_line -n 0 ""
+  assert_line -n 0 "stable dev"
 }
 
 @test "completion bash-it: search - show no options" {