fix: honoring MergeStrategy in docs, change OVERWRITE -> OVERRIDE

[mariogarcia]

Hi there:

Licensing plugin docs mentioned OVERWRITE as mergeStrategy option, but applying plugin it complained with:

* What went wrong:
A problem occurred evaluating root project 'matter'.
> No enum constant org.kordamp.gradle.plugin.base.plugins.MergeStrategy.OVERWRITE

Checking source code I realized it should be OVERRIDE instead of OVERWRITE.

Cheers Mario

[aalmiray]

Thanks! 😁