fix: handle zinit --help (#597)

Signed-off-by: Vladislav Doster <mvdoster@gmail.com>

tests/commands.zunit

@@ -43,6 +43,16 @@
   assert $output contains 'Loaded: '
   assert $state equals 0
 }
+@test 'help' {
+  for cmd in 'help' '-h' '--help'; do
+    run zinit $cmd
+    assert $output contains '—— help                          – usage information'
+    assert $state equals 0
+  done
+  run zinit -help
+  assert $output contains 'Unknown subcommand'
+  assert $state equals 1  
+}
 @test 'self-update' {
   run zinit self-update
   assert $output contains 'Already up-to-date.'

zinit.zsh

@@ -111,7 +111,6 @@ sh|silent|\
 trackbinds|\
 verbose"
 ZINIT[cmds]="\
--help|-h|\
 add-fpath|\
 bindkeys|\
 cclear|cd|cdclear|cdisable|cdlist|cdreplay|cenable|changes|compile|compiled|compinit|completions|create|creinstall|csearch|cuninstall|\
@@ -119,7 +118,7 @@ delete|debug|\
 edit|env-whitelist|\
 fpath|\
 glance|\
-help|\
+help|--help|-h|\
 ice|\
 light|load|\
 man|module|\