Apache License 2 is incompatible with the README

[nkakouros]

The README mentions:

- Update LICENSE with a license of your choice
    Update copyright notices to reflect your license in:
    - NOTICE
    - pom.xml
    - src/main/mal/exampleLang.mal
    - src/test/java/org/mal_lang/examplelang/test/*.java

If someone where to license the derivative work with for example GPLv2 it would be incompatible.

Also, Section 4 of the Apache license requires that the NOTICE file and the copyright notices are kept in derivative works which is the exact opposite of what the README allows someone to do.