Fix example usage of COMPOSE_ENV_FILES

Author: rrjjvv

content/manuals/compose/how-tos/environment-variables/envvars.md

@@ -119,7 +119,7 @@ Specifies which environment files Compose should use if `--env-file` isn't used.
 When using multiple environment files, use a comma as a separator. For example: 
 
 ```console
-COMPOSE_ENV_FILES=.env.envfile1, .env.envfile2
+COMPOSE_ENV_FILES=.env.envfile1,.env.envfile2
 ```
 
 If `COMPOSE_ENV_FILES` is not set, and you don't provide `--env-file` in the CLI, Docker Compose uses the default behavior, which is to look for an `.env` file in the project directory.