Update README.md
Alteração no Slide 54 (Strings)
correcao na classe Banco
Merge branch 'master' of https://github.com/enzomotta/coders.example
Merge branch 'master' into errado

Conflicts:
	src/com/coders/boaspraticas/banco/Banco.java
resolves enzomotta/coders.example#16
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