feat: Translate frontend/src/i18n/en.json in pl

99% of minimum 50% translated source file: 'frontend/src/i18n/en.json'
on 'pl'.

Sync of partially translated files: 
untranslated content is included with an empty translation 
or source language content depending on file format

frontend/src/i18n/pl.json

@@ -275,7 +275,7 @@
   },
   "available_csv_separators": {
     "comma": "Przecinek (,)",
-    "semicolon": "Semicolon (;)",
+    "semicolon": "Średnik (;)",
     "both": "Both (,) and (;)"
   }
 }