Still `new Timber.DebugTree()` cannot be coded in Java

This issue occurs since 5.0.0.
No fixing in 5.0.1.

For Java version, we have to use 4.7.1.

#458 #459
 https://stackoverflow.com/questions/70870740/cannot-resolve-method-planttimber-log-timber-debugtree

If this is unsolvable, please add remarks in `README.me` for new users to use it with Java code.