Initial dutch translation (#561)

* Dutch translations for CONTRIBUTING.

* Dutch translations for README.

* Can't believe I forgot the title :)

* Alphabetize language listings.

* Use a less literal translation.

* Use arabic comma

* remove comma

* use arabic comma

* use arabic comma

* Add Software Hertigate badge

* Translate dates to Dutch.

* Translate names of functions.

Co-authored-by: James Harris <wopian@wopian.me>

CONTRIBUTING.zh_tw.md

@@ -2,6 +2,7 @@
 
 :crossed_flags:
 [English][EN],
+[Nederlands][NL],
 [Português][PT_BR],
 [Türkçe][TR],
 [العربية][AR],
@@ -14,6 +15,7 @@
 [PT_BR]:CONTRIBUTING.pt_br.md
 [TR]:CONTRIBUTING.tr.md
 [ZH_TW]:CONTRIBUTING.zh_tw.md
+[NL]:CONTRIBUTING.nl.md
 
 這個倉庫的原始碼，是透過列印出的紙本輸出，予以手動數位化。所以可能會不小心出現錯字和其他出入。程式碼應當修正到與紙本掃描的輸出一致：