docs(rust,client): use packageName variable for Cargo.toml dependenci…

…es example

modules/openapi-generator/src/main/resources/rust/README.mustache

@@ -24,7 +24,7 @@ This API client was generated by the [OpenAPI Generator](https://openapi-generat
 Put the package under your project folder and add the following to `Cargo.toml` under `[dependencies]`:
 
 ```
-    openapi = { path = "./generated" }
+{{{packageName}}} = { path = "./generated" }
 ```
 
 ## Documentation for API Endpoints