docs(api): adding api examples to DVC and LVC

[MeelahMe]

Closes #5974

• Added HTTP API section to Last Value Cache create.md (POST /api/v3/configure/last_cache)
• Added API delete instructions to Last Value Cache delete.md (DELETE /api/v3/configure/last_cache)
• Added API query examples for both cache types in show.md (system tables) and query.md (cache functions)

[Copilot]

Pull Request Overview

This PR adds comprehensive HTTP API documentation for both Last Value Cache (LVC) and Distinct Value Cache (DVC) operations in InfluxDB 3. The changes provide API alternatives to CLI commands, enabling users to manage caches via REST endpoints.

Key changes:

• Added HTTP API examples for creating, deleting, and querying caches
• Documented API parameter differences from CLI (JSON arrays vs comma-delimited, seconds vs humantime)
• Included response codes and example requests/responses for better usability

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
content/shared/influxdb3-admin/last-value-cache/create.md	Added POST API endpoint documentation with JSON payload examples
content/shared/influxdb3-admin/last-value-cache/delete.md	Added DELETE API endpoint with query parameters and response codes
content/shared/influxdb3-admin/last-value-cache/show.md	Added SQL query API examples for viewing cache information
content/shared/influxdb3-admin/distinct-value-cache/create.md	Added POST API endpoint for DVC creation with parameter format notes
content/shared/influxdb3-admin/distinct-value-cache/show.md	Added SQL query API examples (incorrectly references last_caches table)
content/shared/influxdb3-admin/distinct-value-cache/query.md	Added API examples for querying cached data using last_cache function

[jstirnaman]

Overall, this is really good. I added in the endpoint shortcodes, which include reference links.
We need to add paragraphs to introduce the CLI and API, and then update the frontmatter descriptions with them as well.
Thanks for picking this up!

[MeelahMe]

@jstirnaman do you think we should "add paragraphs to introduce the CLI and API, and then update the frontmatter descriptions with them as well." under this PR or create a new issue for it?