chore: update copy

Author: songquanpeng

web/default/src/components/LoginForm.js

@@ -94,7 +94,7 @@ const LoginForm = () => {
               fluid
               icon='user'
               iconPosition='left'
-              placeholder='用户名'
+              placeholder='用户名 / 邮箱地址'
               name='username'
               value={username}
               onChange={handleChange}