v2.3.2: Add info button to WiFi Manager screen explaining multi-network support

src/i18n_en.h

@@ -146,6 +146,11 @@ static const char* const I18N_EN[] = {
     "WiFi networks",
     "Add network",
     "(empty)",
+
+    "How WiFi networks work",
+    "You can save up to 3 WiFi networks. On boot, the device automatically connects to whichever one it can currently reach.",
+    "Handy for portable use (office, friends, holiday home), for guest + main WiFi on the same router, or if you have multiple access points around the house.",
+    "Remove a saved network anytime via the red 'X' to free up a slot for a new one.",
 };
 
 static_assert(sizeof(I18N_EN) / sizeof(I18N_EN[0]) == (size_t)StringId::COUNT,