fix: document --global on scheduler-k3s report and set

The usage strings for `scheduler-k3s:report` and `scheduler-k3s:set` omitted the `--global` option, which is the only way to reach the scheduler-wide report since a bare `scheduler-k3s:report` iterates every app, and `:report` also omitted `--format stdout|json`. The command listing in the k3s documentation is resynced with the help output, which additionally restores flags that had been dropped from `scheduler-k3s:cluster:add`, `scheduler-k3s:cluster:list`, and `scheduler-k3s:initialize`.

tests/unit/scheduler-k3s-help.bats

@@ -0,0 +1,28 @@
+#!/usr/bin/env bats
+
+load test_helper
+
+setup() {
+  global_setup
+}
+
+teardown() {
+  global_teardown
+}
+
+@test "(scheduler-k3s) scheduler-k3s:help" {
+  run /bin/bash -c "dokku scheduler-k3s"
+  echo "output: $output"
+  echo "status: $status"
+  assert_output_contains "Manage scheduler-k3s settings for an app"
+  help_output="$output"
+
+  run /bin/bash -c "dokku scheduler-k3s:help"
+  echo "output: $output"
+  echo "status: $status"
+  assert_output_contains "Manage scheduler-k3s settings for an app"
+  assert_output "$help_output"
+
+  assert_output_contains "scheduler-k3s:report [<app>|--global] [--format stdout|json] [<flag>]"
+  assert_output_contains "scheduler-k3s:set <app|--global> <property> (<value>)"
+}