[move-ide] Prettier Move plugin install instruction fix (MystenLabs#1…

…6059)

## Description 

A minor documentation fix.

external-crates/move/crates/move-analyzer/prettier-plugin/README.md

@@ -44,7 +44,7 @@ Go to the root directory of the Move package whose files you'd like to format (i
 containing the Move.toml manifest file for this package) and run the following command:
 
 ``` bash
-npm install [email protected] ~/prettier-plugin-move
+npm install [email protected] "$SUI"/external-crates/move/crates/move-analyzer/prettier-plugin
 ```
 
 This will install both the prettier formatter and the plugin in the `./node_modules` directory.