Revert Docker tag [ci skip]

Signed-off-by: Valerian Saliou <valerian@valeriansaliou.name>

README.md

@@ -90,13 +90,13 @@ You might find it convenient to run Sonic via Docker. You can find the pre-built
 First, pull the `valeriansaliou/sonic` image:
 
 ```bash
-docker pull valeriansaliou/sonic:v1.2.2
+docker pull valeriansaliou/sonic:v1.2.1
 ```
 
 Then, seed it a configuration file and run it (replace `/path/to/your/sonic/config.cfg` with the path to your configuration file):
 
 ```bash
-docker run -p 1491:1491 -v /path/to/your/sonic/config.cfg:/etc/sonic.cfg -v /path/to/your/sonic/store/:/var/lib/sonic/store/ valeriansaliou/sonic:v1.2.2
+docker run -p 1491:1491 -v /path/to/your/sonic/config.cfg:/etc/sonic.cfg -v /path/to/your/sonic/store/:/var/lib/sonic/store/ valeriansaliou/sonic:v1.2.1
 ```
 
 In the configuration file, ensure that: