Auto merge of #6081 - sunny:patch-2, r=olleolleolle
Auto merge of #6081 - sunny:patch-2, r=olleolleolle

Fix bundler update instructions in TROUBLESHOOTING

### What was the end-user problem that led to this PR?

Doing the previous command from the TROUBLESHOOTING guide returns an error:

```sh
$ `gem update bundler`
zsh: command not found: Updating
```

### What is your fix for the problem, implemented in this PR?

Removing both ``` ` ``` in the documentation.

mvz/bundler,bundler/bundler,bundler/bundler,mvz/bundler,dilumnavanjana/bundler,dilumnavanjana/bundler