mobile: add Polish language (#2181)

* mobile: add Polish language

* update readme

apps/android/app/build.gradle

@@ -77,7 +77,7 @@ android {
     def isBundle = gradle.getStartParameter().taskNames.find({ it.toLowerCase().contains("bundle") }) != null
 //    if (isRelease) {
         // Comma separated list of languages that will be included in the apk
-    android.defaultConfig.resConfigs("en", "cs", "de", "es", "fr", "it", "nl", "ru", "zh-rCN")
+    android.defaultConfig.resConfigs("en", "cs", "de", "es", "fr", "it", "nl", "pl", "ru", "zh-rCN")
 //    }
     if (isBundle) {
         defaultConfig.ndk.abiFilters 'arm64-v8a', 'armeabi-v7a'

apps/android/app/src/main/java/chat/simplex/app/views/usersettings/Appearance.kt

@@ -236,6 +236,7 @@ private fun LangSelector(state: State<String>, onSelected: (String) -> Unit) {
     "fr" to "Français",
     "it" to "Italiano",
     "nl" to "Nederlands",
+    "pl" to "Polski",
     "ru" to "Русский",
     "zh-CN" to "简体中文"
   )