Updates & fixes for the README Python driver section

[cjbj]

1. In the README, change

Python thin driver

Install thin driver in your Python 3 environment

to:

Python

Install the python-oracledb driver for Oracle Database

because the driver comes with both Thin and Thick modes.

2. Change the install command to the more generic

python3 -m pip install oracledb

3. Change the code to:

   
   import oracledb
   conn = oracledb.connect(user="admin", password="<my_adw_admin_password>", dsn="my_adw_medium", config_dir="/scratch/tls_wallet", wallet_location="/scratch/tls_wallet", wallet_password="***")
   cr = conn.cursor()
   r = cr.execute("SELECT 1 FROM DUAL")
   print(r.fetchall())

[(1,)]

It's better to separate the credentials and not stuff them in the DSN.

Technically the config_dir param isn't needed if the users followed the instructions and set TNS_ADMIN. But users may miss that step, and it won't hurt to set it again.

[aosingh]

Documentation is updated for Python section