Add missing Polish translations and improve existing (#5382)

* Add missing Polish translations and improve existing

* Improve translations

CONTRIBUTING.md

@@ -252,7 +252,7 @@ Languages with less than 90% coverage will be removed in a future Nightscout ver
 | 한국어 (`ko`)|Please volunteer|Needs attention: 80.6%|
 | Norsk (Bokmål) (`nb`)|Please volunteer|OK|
 | Nederlands (`nl`)|[@PieterGit]|OK|
-| Polski (`pl`)|Please volunteer|OK|
+| Polski (`pl`)|[@Bartlomiejsz]|OK|
 | Português (Brasil) (`pt`)|Please volunteer|OK|
 | Română (`ro`)|Please volunteer|OK|
 | Русский (`ru`)|[@apanasef]|OK|

lib/client/d3locales.js

@@ -142,6 +142,21 @@ d3locales.it_IT = {
   shortMonths: ['Gen', 'Feb', 'Mar', 'Apr', 'Mag', 'Giu', 'Lug', 'Ago', 'Set', 'Ott', 'Nov', 'Dic']
 };
 
+d3locales.pl_PL = {
+  decimal: '.',
+  thousands: ',',
+  grouping: [3],
+  currency: ['', 'zł'],
+  dateTime: '%a %b %e %X %Y',
+  date: '%d.%m.%Y',
+  time: '%H:%M:%S',
+  periods: ['AM', 'PM'], // unused
+  days: ['Niedziela', 'Poniedziałek', 'Wtorek', 'Środa', 'Czwartek', 'Piątek', 'Sobota'],
+  shortDays: ['Nie', 'Pn', 'Wt', 'Śr', 'Czw', 'Pt', 'So'],
+  months: ['Styczeń', 'Luty', 'Marzec', 'Kwiecień', 'Maj', 'Czerwiec', 'Lipiec', 'Sierpień', 'Wrzesień', 'Październik', 'Listopad', 'Grudzień'],
+  shortMonths: ['Sty', 'Lu', 'Mar', 'Kw', 'Maj', 'Cze', 'Lip', 'Sie', 'Wrz', 'Pa', 'Lis', 'Gru']
+};
+
 d3locales.pt_BR = {
   decimal: ',',
   thousands: '.',
@@ -212,6 +227,7 @@ d3locales.locale = function locale (language) {
     , fr: 'fr_FR'
     , he: 'he_IL'
     , it: 'it_IT'
+    , pl: 'pl_PL'
     , pt: 'pt_BR'
     , ro: 'ro_RO'
     , ru: 'ru_RU'