Update troubleshooting.md (#1320)

Having a pre-commit the previous documentation failed with

```shell
$ git commit
.husky/pre-commit: 9: /home/user/.huskyrc: [[: not found
```

Using this patch is compatible with /bin/bash

docs/troubleshooting.md

@@ -21,7 +21,7 @@ export NVM_DIR="$HOME/.nvm"
 [ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"
 
 # If you have an .nvmrc file, we use the relevant node version
-if [[ -f ".nvmrc" ]]; then
+if [ -f ".nvmrc" ]; then
   nvm use
 fi
 ```