Update 'note' on distributions metric type doc

[JakeYankovich]

What does this PR do? What is the motivation?

Before:

Note: Because distributions are a new metric type, they should be instrumented under new metric names during submission to Datadog. After: Note: Because distributions metric data is stored differently from other types, any metric name used for a distribution should not be used for any other metric types.

Merge instructions

If a metric was previously a non-distribution type and then submitted as a distribution, this can cause issues. If a metric was previously distribution type and then submitted as a different type, this can also cause issues. The previous note only hints towards the former.

Motivation:

• https://datadoghq.atlassian.net/wiki/spaces/TS/pages/348522308/How-To+Troubleshoot+Distribution+Metrics+Overshadowing
• https://datadog.zendesk.com/agent/tickets/1830663

• [x] Please merge after reviewing

Additional notes

[github-actions[bot]]

Preview links (active after the build_preview check completes)

Modified Files

• https://docs-staging.datadoghq.com/JakeYankovich/distribution-note/metrics/distributions