Add reference to the Datadog plugin in README

[jfree]

What Does This Do

Adds a "See Also" to the README that links to the Datadog plugin for IntelliJ IDEA.

Motivation

Raise awareness of the Datadog plugin, especially the Error Tracking and Live Debugger integrations.

Contributor Checklist

• Format the title according to the contribution guidelines
• Assign the type: and (comp: or inst:) labels in addition to any other useful labels
• Avoid using close, fix, or any linking keywords when referencing an issue
  Use solves instead, and assign the PR milestone to the issue
• Update the CODEOWNERS file on source file addition, migration, or deletion
• Update public documentation with any new configuration flags or behaviors

Jira ticket: [PROJ-IDENT]

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[PerfectSlayer]

💭 thought: ‏I have mixed feelings about this recommendation. How is that related to the project?

❔ question: ‏Can we ever plug org 2 telemetry into it to get internal telemetry from the users? I'm not even sure. Even though, that won't be available to all contributors, only the Datadog ones. And I would not advocate for help contributors can't get.

[jfree]

💭 thought: ‏I have mixed feelings about this recommendation. How is that related to the project?

Fair question. It's relevant for the audience of this project (Java devs in companies that work with Datadog) rather than this project directly. We want to raise awareness of the Datadog plugin, because it has really useful features for Java developers, so this seems like one reasonable avenue. I can totally accept a rejection on the PR though, I understand where you are coming from.

❔ question: ‏Can we ever plug org 2 telemetry into it to get internal telemetry from the users? I'm not even sure. Even though, that won't be available to all contributors, only the Datadog ones. And I would not advocate for help contributors can't get.

I don't think the plugin (when used within Datadog) is seeing telemetry from the Java tracer. Ping me some details about what you collect and how, and I can take a look.