Add x-cmd method to install dive (#550)

- Hi, we have implemented a lightweight [package manager using shell and awk](https://www.x-cmd.com/pkg/).
It helps you download dive release packages from the internet and extract them into a unified directory for management, without requiring root permissions.

- **I mean, can the installation method provided by x-cmd be added to the dive README?**[The installation method for the x command](https://www.x-cmd.com/start/)
  ```sh
  x env use dive
  ```