fix(docs/contributing): correct pnpm link command

Author: stainless-app[bot]

CONTRIBUTING.md

@@ -60,7 +60,7 @@ $ yarn link @digitalocean/gradient
 # With pnpm
 $ pnpm link --global
 $ cd ../my-package
-$ pnpm link -—global @digitalocean/gradient
+$ pnpm link --global @digitalocean/gradient
 ```
 
 ## Running tests