docs: add self-hosted repos example for remote presets. (#3494)

Author: ruanhaojian

docs/guide/plugins-and-presets.md

@@ -198,6 +198,10 @@ GitLab and BitBucket are also supported. Make sure to use the `--clone` option i
 ``` bash
 vue create --preset gitlab:username/repo --clone my-project
 vue create --preset bitbucket:username/repo --clone my-project
+
+# self-hosted repos
+vue create --preset gitlab:my-gitlab-server.com:group/projectname --clone my-project
+vue create --preset direct:ssh://[email protected]/group/projectname.git --clone my-project
 ```
 
 ### Local Filesystem Preset