Fix: replace `uctl` with `flytectl` in OSS docs

[fg91]

Why are the changes needed?

OSS docs mention uctl (cli for Union.ai) instead of flytectl in two locations.

Check all the applicable boxes

• [x] I updated the documentation accordingly.
• [ ] All new and existing tests passed.
• [x] All commits are signed-off.

Docs link

[codecov[bot]]

Codecov Report

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

Project coverage is 61.00%. Comparing base (4cb1473) to head (0718301).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #5501 +/- ## ========================================== - Coverage 61.01% 61.00% -0.01% ========================================== Files 794 794 Lines 51441 51441 ========================================== - Hits 31385 31382 -3 - Misses 17164 17166 +2 - Partials 2892 2893 +1 ``` | [Flag](https://app.codecov.io/gh/flyteorg/flyte/pull/5501/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=flyteorg) | Coverage Δ | | |---|---|---| | [unittests-datacatalog](https://app.codecov.io/gh/flyteorg/flyte/pull/5501/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=flyteorg) | `69.31% <ø> (ø)` | | | [unittests-flyteadmin](https://app.codecov.io/gh/flyteorg/flyte/pull/5501/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=flyteorg) | `58.71% <ø> (-0.03%)` | :arrow_down: | | [unittests-flytecopilot](https://app.codecov.io/gh/flyteorg/flyte/pull/5501/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=flyteorg) | `17.79% <ø> (ø)` | | | [unittests-flytectl](https://app.codecov.io/gh/flyteorg/flyte/pull/5501/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=flyteorg) | `68.03% <ø> (ø)` | | | [unittests-flyteidl](https://app.codecov.io/gh/flyteorg/flyte/pull/5501/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=flyteorg) | `79.04% <ø> (ø)` | | | [unittests-flyteplugins](https://app.codecov.io/gh/flyteorg/flyte/pull/5501/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=flyteorg) | `61.85% <ø> (ø)` | | | [unittests-flytepropeller](https://app.codecov.io/gh/flyteorg/flyte/pull/5501/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=flyteorg) | `57.30% <ø> (ø)` | | | [unittests-flytestdlib](https://app.codecov.io/gh/flyteorg/flyte/pull/5501/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=flyteorg) | `65.82% <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=flyteorg#carryforward-flags-in-the-pull-request-comment) to find out more.

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