Mention plugindev plugin in release notes

In agreement with Hans et al.
Removed filtering of message that is no longer produced.
Changed the behaviour when mutating a configuration whose child has been resolved from an error to a deprecation. This will become an error in Gradle 3.0
Reworked mutation checking in DefaultConfiguration to warn about any change that may affect a child configuration, and to include the configuration that is  being changed in the warning, rather than the configuration that was resolved.
Added deprecation to release notes
Added some more int test coverage for mutation of configurations after resolution
Update int test to use a newer Gradle snapshot.
fix groovydoc url
use https to resolve javadoc packages from oracle; http is no longer working
Next release is 2.2.1
GRADLE-3194 - Fallback to using the machine's local addresses as the remote addresses, when the local host name cannot be resolved to an IP address (eg when offline).
Fixed typo.
Reset the release notes.
Updated release notes.