doc: update android cargo-ndk instructions

cargo-ndk v2 changed command line options. CI already runs with
updated version, so the documentation only need to be updated.
diff --git a/README.md b/README.md
index 68a50e1..5d057a7 100644
--- a/README.md
+++ b/README.md
@@ -312,17 +312,17 @@
 #### NDK version >= 19
 
 For NDK version 19 or higher (21 recommended), you can build in a simpler
-way using [cargo-ndk]. You need to install [cargo-ndk] first.
+way using [cargo-ndk]. You need to install [cargo-ndk] (v2.0 or later) first.
 
 ```bash
  $ cargo install cargo-ndk
 ```
 
 You can build the quiche library using the following procedure. Note that
-`--target` and `--android-platform` are mandatory.
+`-t <architecture>` and `-p <NDK version>` are mandatory.
 
 ```bash
- $ cargo ndk --target aarch64-linux-android --android-platform 21 -- build --features ffi
+ $ cargo ndk -t arm64-v8a -p 21 -- build --features ffi
 ```
 
 See [build_android_ndk19.sh] for more information.
diff --git a/tools/android/build_android_ndk19.sh b/tools/android/build_android_ndk19.sh
index e2cac58..54c6143 100755
--- a/tools/android/build_android_ndk19.sh
+++ b/tools/android/build_android_ndk19.sh
@@ -21,11 +21,9 @@
 
 echo "> building quiche for android API $API_LEVEL..."
 
-for target in \
-    aarch64-linux-android \
-    armv7-linux-androideabi \
-    i686-linux-android
+for arch in arm64-v8a armeabi-v7a x86_64 x86
 do
-    echo "> buliding $target..."
-    cargo ndk --target $target --android-platform $API_LEVEL -- build --features ffi $*
+    echo "> buliding $arch..."
+
+    cargo ndk -t $arch -p $API_LEVEL -- build --features ffi $*
 done