fix: Default value is not set in Redis connection string using enviro…

…nment variable

Removed documentation of Redis connection string supporting default values when using environment variables as it isn't supported

Fixes feast-dev#3669

Signed-off-by: Theodor Mihalache <tmihalac@redhat.com>

docs/how-to-guides/running-feast-in-production.md

@@ -257,17 +257,6 @@ online_store:
     connection_string: ${REDIS_CONNECTION_STRING}
 ```
 
-It is possible to set a default value if the environment variable is not set, with `${ENV_VAR:"default"}`. For instance:
-
-```yaml
-project: my_project
-registry: data/registry.db
-provider: local
-online_store:
-    type: redis
-    connection_string: ${REDIS_CONNECTION_STRING:"0.0.0.0:6379"}
-```
-
 ***
 
 ## Summary