[java] Document that CallSuperFirst/CallSuperLast are Android specific

**Rules:** [CallSuperFirst](https://pmd.github.io/latest/pmd_rules_java_errorprone.html#callsuperfirst) and [CallSuperLast](https://pmd.github.io/latest/pmd_rules_java_errorprone.html#callsuperlast)

These rules make only sense when developing Android apps.