feat(agent-control): update value providers docs

[sigilioso]

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This PR extends the agent-control public docs to update configuration options already released as 1.24.0.

It essentially updates the Secrets providers references to the new naming Value providers and includes the documentation for missing value providers.

For more information, please check the Agent Control repository:

• Variable Interpolation in-repo docs.
• feat(k8s): support ConfigMap value loader [NR-610910] newrelic-agent-control#2872
• chore: rename secrets_providers to value_provider newrelic-agent-control#2864

[github-actions]

Hi @sigilioso 👋

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[PallaviWrite]

netlify build fork

[svc-docs-eng-opensource-bot]

✅ Your PR has been mirrored to our repository as PR #25707.
Commit: 77cbdb0080be52074f961a750b4df297ead64755 (77cbdb0)
Our workflows will run in the mirrored PR linked above.
🚀 If the build is successful, a Netlify preview will be available shortly at: https://sigilioso-feat-agent-control-value-pro--docs-website-netlify.netlify.app

[PallaviWrite]

netlify build fork

[svc-docs-eng-opensource-bot]

✅ Your updates have been mirrored to our repository in PR #25707.
Commit: a18ce1bf4f66b0203850166de00eaf476512f6a3 (a18ce1b)
Our workflows will run in the mirrored PR linked above.
🚀 If the build is successful, a Netlify preview will be updated shortly at: https://sigilioso-feat-agent-control-value-pro--docs-website-netlify.netlify.app

[MunhozThiago]

LGTM but I am in doubt about explicitly separating Secret Providers in a separate section. Two reasons:

1. SEO and easier to find only regarding secret providers support
2. In the future we will add other providers support

WDYT?

[sigilioso]

LGTM but I am in doubt about explicitly separating Secret Providers in a separate section. Two reasons:

1. SEO and easier to find only regarding secret providers support
2. In the future we will add other providers support

WDYT?

The whole Secret Provider term was renamed to Value Provider and that why I also renamed the section. Besides, new (future) providers should fit into value providers, otherwise they would be part of a completely different feature. That said, making it easy to find is really important so I added back the previous section (with the corresponding reference to value providers).

Check 1a2711c

LMKWYT

[PallaviWrite]

Got approval from @MunhozThiago via Slack: https://newrelic.slack.com/archives/C0DSGL3FZ/p1789458945116959

[PallaviWrite]

lgtm