docs(readme): use shelltime.xyz URLs and improve documentation links

Replace raw GitHub install URL with shorter shelltime.xyz/i, link to
shelltime.xyz for guides and help documentation.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: AnnatarHe

README.md

@@ -7,21 +7,20 @@ Welcome to shelltime! This guide will help you install the necessary tools using
 You can install shelltime tools by running the following command in your terminal:
 
 ```bash
-curl -sSL https://raw.githubusercontent.com/shelltime/installation/master/install.bash | bash
+curl -sSL https://shelltime.xyz/i | bash
 ```
 
 ## What Next?
 
 Once the installation script finishes successfully, you should be able to track your shell time.
 
-just by typing `shelltime init`.
-
-Please refer to the main shelltime documentation for more details on how to use the tools.
+Visit [shelltime.xyz](https://shelltime.xyz) for guides and usage documentation.
 
 ## Having Issues?
 
 If you encounter any problems during the installation or have any questions, please:
 *   Check the output of the script for any error messages.
+*   Visit [shelltime.xyz](https://shelltime.xyz) for general help and documentation.
 *   [Open an issue on our GitHub repository](https://github.com/shelltime/cli/issues/new/choose)
 
 ---