Update CHANGELOG.md prior to v2.7.1 release.

Author: abernix

CHANGELOG.md

@@ -6,6 +6,10 @@ The version headers in this history reflect the versions of Apollo Server itself
 
 > The changes noted within this `vNEXT` section have not been released yet.  New PRs and commits which introduce changes should include an entry in this `vNEXT` section as part of their development.  When a release is being prepared, a new header will be (manually) created below and the the appropriate changes within that release will be moved into the new section.
 
+- _Nothing yet!_
+
+### v2.7.1
+
 - `apollo-engine-reporting`: If an error is thrown by a custom variable transform function passed into the reporting option `sendVariableValues: { transform: ... }`, all variable values will be replaced with the string `[PREDICATE_FUNCTION_ERROR]`.
 - `apollo-server-express: Typing fix for the `connection` property, which was missing from the `ExpressContext` interface.  [PR #2959](https://github.com/apollographql/apollo-server/pull/2959)
 - `@apollo/gateway`: Ensure execution of correct document within multi-operation documents by including the `operationName` in the cache key used when caching query plans used in federated execution. [PR #3084](https://github.com/apollographql/apollo-server/pull/3084)