Add reference to manifest entries in expand subcommand help (bugfix)

[pieqq]

Description

Following https://github.com/canonical/checkbox/pull/1489, the expand subcommand now also lists manifest entries. This is now reflected in the subcommand help.

Resolved issues

Documentation

$ checkbox-cli expand --help
usage: checkbox-cli [-h] [-f FORMAT] TEST_PLAN

Expand a given test plan: display all the jobs, templates and manifest entries that are defined in this test plan and that  would be executed if ran. This is useful to visualize the full list of units called for complex test plans that consist of many nested parts with different 'include' and 'exclude' sections.

NOTE: the elements listed here are not sorted by execution order. To see the execution order, please use the 'list-bootstrapped' command instead.

positional arguments:
  TEST_PLAN             test-plan id to expand

options:
  -h, --help            show this help message and exit
  -f FORMAT, --format FORMAT
                        output format: 'text' or 'json' (default: text)

Tests

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 47.78%. Comparing base (60b6702) to head (59cd535). Report is 2 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1558 +/- ## ======================================= Coverage 47.78% 47.78% ======================================= Files 370 370 Lines 39751 39751 Branches 6720 6720 ======================================= Hits 18997 18997 Misses 20042 20042 Partials 712 712 ``` | [Flag](https://app.codecov.io/gh/canonical/checkbox/pull/1558/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=canonical) | Coverage Δ | | |---|---|---| | [checkbox-ng](https://app.codecov.io/gh/canonical/checkbox/pull/1558/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=canonical) | `68.28% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=canonical#carryforward-flags-in-the-pull-request-comment) to find out more.

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.