Update README.md

[maddogdev01]

Replace param value for DD_SITE with text, it does not display properly.

What does this PR do?

Replaces: "<code class="js-region-param region-param" data-region-param="dd_site"></code>",
with "REPLACE ME WITH YOUR DATADOG SITE"

Motivation

The parameter that should automatically display the Datadog site on the page does not appear to work in a code block. The displayed value is therefore incorrect.

Testing Guidelines

Used previewed changes button

Additional Notes

Maybe the parameter value can be fixed to detect the site automatically instead?

Types of changes

• Bug fix
• New feature
• Breaking change
• Misc (docs, refactoring, dependency upgrade, etc.)

Check all that apply

• This PR's description is comprehensive
• This PR contains breaking changes that are documented in the description
• This PR introduces new APIs or parameters that are documented and unlikely to change in the foreseeable future
• This PR impacts documentation, and it has been updated (or a ticket has been logged)
• This PR's changes are covered by the automated tests
• This PR collects user input/sensitive content into Datadog
• This PR passes the integration tests (ask a Datadog member to run the tests)
• This PR passes the unit tests
• This PR passes the installation tests (ask a Datadog member to run the tests)