[Example] update buffer data (filter example)

[Example] update buffer data (filter example)

Add code to update label string from passed buffer.
1. update textoverlay with max score
2. update python example and document

Error to be fixed later: cannot link converter and filter.
To fix this issue, change tflite dim for caps negotication.

**Self evaluation:**
1. Build test: [*]Passed [ ]Failed [ ]Skipped
2. Run test: [ ]Passed [ ]Failed [*]Skipped

Signed-off-by: Jaeyun Jung <jy1210.jung@samsung.com>