Update data_source.md - to add a mandatory argument required in the datasource query api request body

[Keetmalin]

This adds a mandatory value required in the request body when querying the datasource API

What is this feature?

Updating the HTTP_API Docs for developers

Why do we need this feature?

This enables the proper usage of this specific API. (Which is the query datasource api). If we try this API without the suggested change in this PR, this API throws an error.

Who is this feature for?

All developers using the Grafana Datasource Query API

Which issue(s) does this PR fix?:

Fixes #

Special notes for your reviewer:

Please check that:

• [ ] It works as expected from a user's perspective.
• [ ] If this is a pre-GA feature, it is behind a feature toggle.
• [x] The docs are updated, and if this is a notable improvement, it's added to our What's New doc.

[CLAassistant]

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1 out of 2 committers have signed the CLA.

:white_check_mark: Eve832
:x: Keet Malin Sugathadasa

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[Eve832]

Hi @Keetmalin, thank you for your contribution, can you please sign the CLA?

[Eve832]

@josmperez can you please confirm the accuracy of this change or add a reviewer that can?

[github-actions[bot]]

This pull request has been automatically marked as stale because it has not had activity in the last 30 days. It will be closed in 2 weeks if no further activity occurs. Please feel free to give a status update or ping for review. Thank you for your contributions!

[josmperez]

Hi @Keetmalin - Could you please resolve the comment by @svennergr so that this PR can move along?

[github-actions[bot]]

This pull request has been automatically marked as stale because it has not had activity in the last 30 days. It will be closed in 2 weeks if no further activity occurs. Please feel free to give a status update or ping for review. Thank you for your contributions!

[github-actions[bot]]

This pull request has been automatically marked as stale because it has not had activity in the last 30 days. It will be closed in 2 weeks if no further activity occurs. Please feel free to give a status update or ping for review. Thank you for your contributions!

[github-actions[bot]]

This pull request has been automatically closed because it has not had any further activity in the last 2 weeks. Thank you for your contributions!