Restructure influxdb3 /plugins for step-by-step clarity

[MeelahMe]

**Objective:

To revise the /plugins section to be more structured and step-by-step than it is now. The goal is to make it easier for users to understand how plugins work, how to configure them, and how to build or extend them—especially for those who are new to InfluxDB 3 or plugin-based architectures.

What the feature does and why it’s useful

• Transforms the current /plugins documentation into a more linear, guided experience
• Helps users understand the purpose, setup, and customization of plugins
• Reduces confusion and improves onboarding by clearly walking through key workflows
• How to use it

Once updated, users should be able to:

• Understand what plugins are and how they fit into the system
• Follow clear, step-by-step instructions to enable, configure, and test plugins
• Extend or write their own plugins, if applicable

part of #5857
closes #5951

[Copilot]

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (2)

content/shared/v3-core-plugins/extended-plugin-api.md:189

• [nitpick] The placeholder 'METHOD' and 'PARAMETERS' may confuse users. Consider either replacing these with concrete examples or adding a clarifying comment that indicates these are placeholders.

influxdb3_local.cache.METHOD(PARAMETERS)

content/shared/v3-core-plugins/extended-plugin-api.md:95

• [nitpick] Ensure that converting a float with no decimal component to an integer and appending '.0' meets the intended behavior and formatting requirements. Verify this behavior remains consistent with all usage scenarios.

self.fields[key] = f"{int(value)}.0" if value % 1 == 0 else str(value)

[Copilot]

Pull Request Overview

This PR restructures the /plugins documentation to provide a clearer, step-by-step guide on how to use and extend InfluxDB 3 plugins. Key changes include:

• Addition of a comprehensive, example-driven extended plugin API documentation file.
• Refinement of the menu naming in enterprise plugin documentation for consistency.
• Creation of two new extended plugin reference pages (enterprise and core) linking to the shared extended plugin API source.

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

File	Description
content/shared/v3-core-plugins/extended-plugin-api.md	New detailed documentation with code examples and best practices for plugin API usage.
content/influxdb3/enterprise/plugins.md	Updated menu item naming for improved consistency.
content/influxdb3/enterprise/extended-plugin.md	New enterprise page referencing the shared extended plugin API documentation.
content/influxdb3/core/extended-plugin.md	New core page referencing the shared extended plugin API documentation.

[Copilot]

Pull Request Overview

This PR restructures the InfluxDB 3 plugins documentation to provide a more step-by-step and guided experience for users. Key changes include:

• Adding a new shared extended plugin API documentation file with detailed code samples.
• Updating the enterprise and core plugin extension files to source from the shared API document.
• Refining menu naming and presentation for clarity.

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

File	Description
content/shared/extended-plugin-api.md	New, detailed documentation for the shared plugin API, complete with code examples and usage guidelines.
content/influxdb3/enterprise/plugins.md	Minor update to the menu name for stylistic consistency.
content/influxdb3/enterprise/extend-plugin.md	New documentation file extending plugins by sourcing shared API content.
content/influxdb3/core/extend-plugin.md	New documentation file extending plugins by sourcing shared API content, with slight naming differences.

Comments suppressed due to low confidence (2)

content/influxdb3/core/extend-plugin.md:7

• [nitpick] The menu name here differs from the enterprise version ('Extend plugins'); consider aligning the naming across both files for consistency.

    name: Extended plugins

content/influxdb3/enterprise/plugins.md:8

• [nitpick] The change to 'Processing engine' appears intended for stylistic consistency; please confirm that this aligns with the overall documentation style.

    name: Processing engine and Python plugins