Fix first-run location screen text overlapping buttons, add native address search tip to presets info screen and README

Shortens the first-run location screen's body text in all 6 languages
and makes its buttons follow the text's actual height instead of a
fixed screen position - the longer German translation previously ran
underneath the "Enter Address"/"Skip" buttons, making it unreadable.

Adds a new info paragraph to the Location Presets "?" screen (all 6
languages) pointing to the native "Search by address" option added in
the previous commit, plus the same tip to the README's Getting Started
section.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/i18n_en.h

@@ -217,9 +217,11 @@ static const char* const I18N_EN[] = {
     "Try again",
     "Cancel",
     "Set Your Exact Location",
-    "Automatic IP-based location can easily be 20-30 km off - you might hear a plane overhead while the radar stays empty. Enter your address now for exact coordinates and a much better experience. The proximity LED will then really blink in sync with the aircraft above you. You can also do this later anytime via Menu > Flight Options > Location Presets.",
+    "Automatic IP-based location can be 20-30 km off. Enter your address for exact coordinates - the proximity LED will then really blink in sync with the aircraft above you. You can do this later anytime via Location Presets.",
     "Enter Address",
     "Skip",
+
+    "Tip: use the \"Search by address\" button when adding a preset (\"+\") to get exact coordinates for your address instantly - much more accurate than automatic IP-based location, which can easily be 20-30 km off. With your exact location set, the proximity LED really does blink in sync with the aircraft you can hear overhead.",
 };
 
 static_assert(sizeof(I18N_EN) / sizeof(I18N_EN[0]) == (size_t)StringId::COUNT,