fix: enum docs for trigger_actions

[stebenz]

Definition of Ready

• [ ] Short description of the feature/issue is added in the pr description
• [ ] PR is linked to the corresponding user story
• [ ] Acceptance criteria are met
• [ ] All open todos and follow ups are defined in a new ticket and justified
• [ ] Deviations from the acceptance criteria and design are agreed with the PO and documented.
• [ ] No debug or dead code
• [ ] My code has no repetitions
• [ ] All non-functional requirements are met
• [ ] The generic lifecycle acceptance test passes for affected resources.
• [ ] Examples are up-to-date and meaningful. The provider version is incremented.
• [ ] Docs are generated.
• [ ] Code is generated where possible.

closes #147

[codecov[bot]]

Codecov Report

Attention: 11 lines in your changes are missing coverage. Please review.

Comparison is base (035db0b) 63.32% compared to head (e9153b9) 63.29%. Report is 5 commits behind head on main.

Files	Patch %	Lines
zitadel/helper/helper.go	0.00%	11 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #160 +/- ## ========================================== - Coverage 63.32% 63.29% -0.04% ========================================== Files 159 159 Lines 12840 12850 +10 ========================================== + Hits 8131 8133 +2 - Misses 3427 3435 +8 Partials 1282 1282 ``` | [Flag](https://app.codecov.io/gh/zitadel/terraform-provider-zitadel/pull/160/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zitadel) | Coverage Δ | | |---|---|---| | [acceptance-tests](https://app.codecov.io/gh/zitadel/terraform-provider-zitadel/pull/160/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=zitadel) | `63.29% <15.38%> (-0.04%)` | :arrow_down: | 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=zitadel#carryforward-flags-in-the-pull-request-comment) to find out more.

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