Add rtl_tcp_andro as submodule for SDR driver app

RTL-SDR + HackRF native Android driver (iqsrc:// protocol).
Auto-installs APK during module flash if built. Build docs
updated with instructions.

build.sh

@@ -5,14 +5,31 @@ cd "$(dirname "$0")"
 ZIP="driver-manager-v1.0.0.zip"
 rm -f "$ZIP"
 
-zip -r9 "$ZIP" \
-    module.prop \
-    customize.sh \
-    post-fs-data.sh \
-    service.sh \
-    system.prop \
-    system/ \
-    webroot/ \
+# Include built APK if available
+mkdir -p apk
+RTL_APK="tools/rtl_tcp_andro/app/build/outputs/apk/release/app-release-unsigned.apk"
+if [ -f "$RTL_APK" ]; then
+    cp "$RTL_APK" apk/rtl_tcp_andro.apk
+    echo "Including rtl_tcp_andro APK"
+fi
+
+FILES=(
+    module.prop
+    customize.sh
+    post-fs-data.sh
+    service.sh
+    system.prop
+    system/
+    webroot/
+    BUILDING_MODULES.md
+)
+
+# Include APK dir if it has files
+if [ -f "apk/rtl_tcp_andro.apk" ]; then
+    FILES+=(apk/)
+fi
+
+zip -r9 "$ZIP" "${FILES[@]}" \
     -x "*.git*" "build.sh" "tools/*" "README*"
 
 echo "Built: $ZIP ($(du -h "$ZIP" | cut -f1))"