chore: encase messenger config in .env.example in single quotes (#89)

.env.example

@@ -1,3 +1,8 @@
 SNAPSHOTDIR=./snapshot/*.tar.zst
-PLUGIN_MESSENGER_CONFIG={messenger_type="Redis", connection_config={redis_connection_str="redis://:[email protected]:6379"}}
-SNAPSHOT_REDIS_CONNECTION_STR='redis://localhost:6379'
+# can be omitted for snapshot processing
+PLUGIN_MESSENGER_CONFIG='{messenger_type="Redis", connection_config={redis_connection_str="redis://:[email protected]:6379"}}'
+SNAPSHOT_REDIS_CONNECTION_STR=redis://localhost:6379 # ensure no quotes are put here because docker does not parse quoted env correctly
+
+# please do not remove the following line from this example
+# remove when creating the actual env file
+# vim: set ft=bash