[onert] add docs for nnfwapi package

This commit add README.md file including how to use nnfw python API with nnfwapi package.

ONE-DCO-1.0-Signed-off-by: KangInyeong kiyoog02@gmail.com
Co-authored-by: blue4683 <an4683@gmail.com>
Co-authored-by: jaemaning <lovesay00@naver.com>
Co-authored-by: phj799 <phj799@naver.com>
Co-authored-by: seohhh <shy1624@naver.com>
Co-authored-by: jeonghwanin <jhpc0128@naver.com>

infra/nnfw/python/README.md

@@ -0,0 +1,46 @@
+# nnfwapi package
+
+`nnfwapi` is a package to run `nnpackage` with nnfw python API.
+
+This package includes nnfw python API module resulted from runtime build.
+
+It is provided separately according to each architecture(x86_64, armv7l, aarch64) from `nnfwapi/libnnfw_api_pybind.py` interface.
+
+## Requirement
+
+`nnfwapi` should be installed from PyPI.
+
+```
+$ pip install nnfwapi
+```
+
+By specifying the version, you can use a specific version of the package.
+
+```
+$ pip install nnfwapi==0.1.0
+```
+
+## Usage
+
+This definition have to be set on the top of the script used nnfw python API.
+
+```
+from nnfwapi.libnnfw_api_pybind import *
+```
+
+## Packaging and Publishing
+
+`pack.sh` is written for publishing this package to PyPI easily.
+
+```
+$ sudo apt install twine
+```
+For publishing the package, twine should be installed.
+
+Execute this command, then the tasks such as copying modules, packaging, and publishing are automatically performed.
+
+```
+sh pack.sh
+```
+
+Before publishing, be carefule to edit the information on `setup.py` such as version, description, etc.

infra/nnfw/python/nnfwapi/libnnfw_api_pybind.py

@@ -23,7 +23,9 @@ def nnfw_session(*args):
     elif (num == 3):
         return libnnfw_api_pybind.nnfw_session(args[0], args[2], args[1])
     else:
-        print("TypeError: nnfw_session() takes 2(MODEL, BACKEND) or 3(MODEL, BACKEND, OPERATION) positional arguments but {} were given".format(num))
+        print(
+            "TypeError: nnfw_session() takes 2(MODEL, BACKEND) or 3(MODEL, BACKEND, OPERATION) positional arguments but {} were given".
+            format(num))
         return