Fix: README adjusted to poky branch dora
Fix: README adjusted to poky branch dora

fd215d7c which forwards qt4-embedded to 4.8.5 depends on dora instead
of dylan. This should also be reflected in the READMEs build instructions.

linux4sam/meta-atmel,linux4sam/meta-atmel,linux4sam/meta-atmel,alexandrebelloni/meta-atmel,kraj/meta-atmel,koenkooi/meta-atmel,linux4sam/meta-atmel,alexandrebelloni/meta-atmel,kraj/meta-atmel,kraj/meta-atmel,linux4sam/meta-atmel,koenkooi/meta-atmel,koenkooi/meta-atmel,alexandrebelloni/meta-atmel