Fix docs (#3719)

Summary:
Pull Request resolved: #3719

Need to `mkdir /data/local/tmp/executorch`

Created from CodeHub with https://fburl.com/edit-in-codehub

Reviewed By: cccclai

Differential Revision: D57735464

fbshipit-source-id: 09b7c275303c7f5952f6b80036468a265b57845f

Author: kirklandsign

docs/source/runtime-build-and-cross-compilation.md

@@ -146,6 +146,7 @@ cmake -DCMAKE_TOOLCHAIN_FILE=/Users/{user_name}/Library/Android/sdk/ndk/25.2.951
 cd  ..
 cmake --build  cmake-android-out  -j9
 
+adb shell mkdir -p /data/local/tmp/executorch
 # push the binary to an Android device
 adb push  cmake-android-out/executor_runner  /data/local/tmp/executorch
 # push the model file