docs: improve documentation

Author: raphaelstolt

README.md

@@ -89,7 +89,7 @@ with at least __one link__ is available.
 ### Initialising a llms.txt file via the included CLI
 
 ```bash
-bin/llms-txt init <file-name>
+bin/llms-txt init [<llms-txt-file>]
 
 Created llms txt file llms.txt.