README.md: update some language labels (#9041)

linguistically correct

README.md

@@ -129,9 +129,9 @@ This project lists books and other resources grouped by genres:
 + [Arabic / al arabiya / العربية](courses/free-courses-ar.md)
 + [Bengali / বাংলা](courses/free-courses-bn.md)
 + [Bulgarian / български](courses/free-courses-bg.md)
-+ [Chinese](courses/free-courses-zh.md)
++ [Chinese / 中文](courses/free-courses-zh.md)
 + [English](courses/free-courses-en.md)
-+ [Finnish](courses/free-courses-fi.md)
++ [Finnish / suomi / suomen kieli](courses/free-courses-fi.md)
 + [French / français](courses/free-courses-fr.md)
 + [German / Deutsch](courses/free-courses-de.md)
 + [Greek / ελληνικά](courses/free-courses-el.md)
@@ -182,7 +182,7 @@ Free Podcasts and Screencasts:
 + [Arabic / al Arabiya / العربية](casts/free-podcasts-screencasts-ar.md)
 + [Chinese / 中文](casts/free-podcasts-screencasts-zh.md)
 + [Czech / čeština / český jazyk](casts/free-podcasts-screencasts-cs.md)
-+ [Dutch](casts/free-podcasts-screencasts-nl.md)
++ [Dutch / Nederlands](casts/free-podcasts-screencasts-nl.md)
 + [English](casts/free-podcasts-screencasts-en.md)
 + [Finnish / Suomi](casts/free-podcasts-screencasts-fi.md)
 + [French / français](casts/free-podcasts-screencasts-fr.md)