fix: update vSphere plugin documentation and configuration examples

[NguyenHoangSon96]

Closes 26912

• My steps to fix:

1. Check out the source telegraf to my local.
2. Run go run ./cmd/telegraf config > etc/telegraf.conf command to generate etc/telegraf.conf file.
3. Tweak the src/writeData/utils/updateTelegrafPlugins.mjs so it will get contents from my local influxdata/telegra/etc/telegraf.conf instead of the remote repository /influxdata/telegraf.
4. Run telegraf-plugins:update command to generate new contents for md and conf files.
5. Create this PR.

This is just a very primitive implementation of the updateTelegrafPlugins.mjs to make the script work
updateTelegrafPlugins.txt

• Some thoughts:

1. I don't know how these things should work exactly; this is just my assumption. If my fixes are not correct, then I will just manually remove the - at the beginning of the .conf file.
2. If this is correct, then we should update the src/writeData/utils/README.md guidance and the src/writeData/utils/updateTelegrafPlugins.mjs script file to get contents from etc/telegraf.conf in the local repository, not the remote.

• Before the fix, there is a - at the beginning of the file.

Screen.Recording.2025-10-22.at.09.55.53.mov

• After I modify src/writeData/utils/updateTelegrafPlugins.mjs and run the command telegraf-plugins:update, the - at the beginning of the file disappears.

Screen.Recording.2025-10-22.at.10.01.23.mov

Checklist

Authors and Reviewer(s), please verify the following:

• A PR description, regardless of the triviality of this change, that communicates the value of this PR
• Well-formatted conventional commit messages that provide context into the change
• Documentation updated or issue created (provide link to issue/PR)
• Signed CLA (if not already signed)
• Feature flagged, if applicable