Add CHANGELOG.md for #3825.

Ref: #3825

CHANGELOG.md

@@ -7,7 +7,7 @@ The version headers in this history reflect the versions of Apollo Server itself
 
 ### v2.11.0
 
-- _Nothing yet! Stay tuned._
+- The range of accepted `peerDepedencies` versions for `graphql` has been widened to include `graphql@^15.0.0-rc.2` so as to accommodate the latest release-candidate of the `graphql@15` package, and an intention to support it when it is finally released on the `latest` npm tag.  While this change will subdue peer dependency warnings for Apollo Server packages, many dependencies from outside of this repository will continue to raise similar warnings until those packages own `peerDependencies` are updated.  It is unlikely that all of those packages will update their ranges prior to the final version of `graphql@15` being released, but if everything is working as expected, the warnings can be safely ignored. [PR #3825](https://github.com/apollographql/apollo-server/pull/3825)
 
 ### v2.10.1