chore(release): 6.0.6

Merge pull request webpack-contrib#453 from webpack-contrib/Release/6…

….0.5

Release/6.0.5

Merge pull request webpack-contrib#449 from webpack-contrib/Release/6…

….0.4

Release/6.0.4

6.0.3

6.0.2

6.0.1

Merge pull request webpack-contrib#375 from jtangelder/release/6.0.0

Release/6.0.0

5.0.1

5.0.0

Merge pull request webpack-contrib#331 from jtangelder/update-changelog

Update CHANGELOG.md