Documentation should include from which Jenkins release the content applies

[daniel-beck]

jenkinsci/matrix-auth-plugin#159 updates the core dependency but it's not immediately clear why.

I know enough to find #264 and then jenkinsci/jenkins@1ec59c7 so that explains it, but documentation should still specify from when it applies so readers don't need to know how the sausage is made to be able to use it.

This isn't unique to the "Dialogs" page: looking through the various pages, none of them specify a required core release.