Update README.md

Portuguese > Português (as it is in portuguese language)

README.md

@@ -8,7 +8,7 @@ Translations:
 * [简体中文](README_zh-CN.md) - ???
 * [Français](README_fr.md)
 * [日本語](README_ja.md)
-* [Portuguese](README_ptBR.md)
+* [Português](README_ptBR.md)
 * [Español](README_es.md)
 * [Română](README_ro.md)
 * [Русский](README_ru.md)