add security modes support:SSL, PLAINTEXT.

edit README.md

Author: stanislav-gabdulgaziev

README.md

@@ -26,14 +26,25 @@ pip install -r requirements.txt
 The Python code can be run in bash with the following,
 in SSL security protocol:
 ```bash
-python main.py --security-protocol ssl --cert-folder ~/kafkaCerts/ \
+python main.py --security-protocol ssl 
+ --cert-folder ~/kafkaCerts/ \
  --host kafka-<name>.aivencloud.com \
  --port 13041 \
  --topic-name pizza-orders \
  --nr-messages 0 \
  --max-waiting-time 0
 ```
+in PLAINTEXT security protocol:
+```bash
+python main.py --security-protocol plaintext 
+ --host your-kafka-broker-host \
+ --port 9092 \
+ --topic-name pizza-orders \
+ --nr-messages 0 \
+ --max-waiting-time 0
+```
 Where
+* `security-protocol`: Security protocol for Kafka. PLAINTEXT or SSL are supported.
 * `cert-folder`: points to the folder containing the Apache Kafka certificates (see [blog post](https://aiven.io/blog/create-your-own-data-stream-for-kafka-with-python-and-faker?utm_source=github&utm_medium=organic&utm_campaign=blog_art&utm_content=post) for more)
 * `host`: the Apache Kafka host
 * `port`: the Apache Kafka port