Add RSS comment for v5.6.185 (#587)

<!-- Explain the changes introduced in your PR -->
Closes sourcegraph/devx-support#1185

This adds the RSS Comment for v5.6.185

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Author: BolajiOlajide

docs/CHANGELOG.mdx

@@ -6,6 +6,8 @@ All notable changes to Sourcegraph are documented in this file.
 
 # v5.6.185
 
+{/* RSS={"version":"v5.6.185", "releasedAt": "2024-08-08"} */}
+
 ### Uncategorized
 
 - [Backport 5.6.x] Changing azureUseDeprecatedCompletionsAPIForOldModels to default to true [#64371](https://github.com/sourcegraph/sourcegraph/pull/64371) Backport 3b16059588e5eff69e00ed56a489ac8560a70d8e from #64347