complete: zsh: add missing sub cmd completion candidates

Add missing 'restore' and 'switch' sub commands to zsh completion
candidate output. E.g.

  $ git re<tab>
  rebase    -- forward-port local commits to the updated upstream head
  reset     -- reset current HEAD to the specified state
  restore   -- restore working tree files

  $ git s<tab>
  show      -- show various types of objects
  status    -- show the working tree status
  switch    -- switch branches

Signed-off-by: Terry Moschou <tmoschou@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/completion/git-completion.zsh

@@ -150,9 +150,11 @@ __git_zsh_cmd_common ()
 	push:'update remote refs along with associated objects'
 	rebase:'forward-port local commits to the updated upstream head'
 	reset:'reset current HEAD to the specified state'
+	restore:'restore working tree files'
 	rm:'remove files from the working tree and from the index'
 	show:'show various types of objects'
 	status:'show the working tree status'
+	switch:'switch branches'
 	tag:'create, list, delete or verify a tag object signed with GPG')
 	_describe -t common-commands 'common commands' list && _ret=0
 }