Refine run methods with arguments instead of environments (#164)

#### What this PR does/Why we need it?

1. Refine Docker run command and Docker compose file with arguments instead of environments for Halo 2.1 and 2.2.0-SNAPSHOT.
2. Change environments description into arguments description.

#### Which issue(s) this PR fixes:

Fix https://github.com/halo-dev/docs/issues/163

```release-note
None
```

versioned_docs/version-2.1/intro.md

@@ -39,10 +39,10 @@ docker run \
   --name halo \
   -p 8090:8090 \
   -v ~/.halo2:/root/.halo2 \
-  -e HALO_EXTERNAL_URL=http://localhost:8090/ \
-  -e HALO_SECURITY_INITIALIZER_SUPERADMINUSERNAME=admin \
-  -e HALO_SECURITY_INITIALIZER_SUPERADMINPASSWORD=P@88w0rd \
-  halohub/halo:2.0
+  halohub/halo:2.1 \
+  --halo.external-url=http://localhost:8090/ \
+  --halo.security.initializer.superadminuser=admin \
+  --halo.security.initializer.superadminpassword=P@88w0rd
 ```
 
 以上仅作为体验使用，详细部署文档请查阅：<https://docs.halo.run/getting-started/install/docker-compose>