Delete the magic_wand example (#1851)

We are moving in a direction where the goal of the code within the TFLM examples directory is to illustrate how to use different functionality of the framework.

Examples that don't exercise very different functionality from the others can be removed.

BUG=cleanup

Author: advaitjain

tensorflow/lite/micro/docs/new_platform_support.md

@@ -45,7 +45,6 @@ only the sources that are necessary to build the code TFLM library.
 python3 tensorflow/lite/micro/tools/project_generation/create_tflm_tree.py \
   -e hello_world \
   -e micro_speech \
-  -e magic_wand \
   -e person_detection \
   /tmp/tflm-tree
 ```
@@ -114,7 +113,7 @@ optimized kernel implementations (and associated third party dependencies).
 For example:
 ```
 python3 tensorflow/lite/micro/tools/project_generation/create_tflm_tree.py \
-  -e hello_world -e magic_wand -e micro_speech -e person_detection \
+  -e hello_world -e micro_speech -e person_detection \
   --makefile_options="TARGET=cortex_m_generic OPTIMIZED_KERNEL_DIR=cmsis_nn TARGET_ARCH=project_generation" \
   /tmp/tflm-cmsis
 ```