Fix 'downloadLanguageKeys' property name

Author: jpomykala

README.md

@@ -338,7 +338,7 @@ uploadOptions:
 
 # Properties used by 'download' command
 downloadPath: ./output-translations/messages_{lang}.json
-downloadLanguageKey: ['de-DE', 'fr-FR', 'pl-PL']
+downloadLanguageKeys: ['de-DE', 'fr-FR', 'pl-PL']
 downloadFormat: single-language-json
 downloadOptions:
   - WRITE_NESTED

simplelocalize.yml

@@ -39,7 +39,7 @@ uploadFormat: single-language-json
 downloadPath: ./translations_{lang}.json
 
 # Specify language keys which you want to download, by default all languages are downloaded.
-# downloadLanguageKey: ['pl', 'es']
+# downloadLanguageKeys: ['pl', 'es']
 
 # Output format for translations: https://simplelocalize.io/docs/general/file-formats/
 downloadFormat: single-language-json