docs/user/troubleshooting: Drop 'sh' highlighting from error message
docs/user/troubleshooting: Drop 'sh' highlighting from error message

This isn't shell content, so we shouldn't be highlighting it.  Before
this commit, GitHub was styling 'in' (which is a shell keyword):

  $ curl -s https://github.com/openshift/installer/blob/fffc4775376d0758ac31e17126f6d401658c9012/docs/user/troubleshooting.md#etcd-is-not-running | grep 'Error signing'
  <div class="highlight highlight-source-shell"><pre>Error signing CSR provided <span class="pl-k">in</span> request from agent: error parsing profile: invalid organization</pre></div>

derekhiggins/installer,derekhiggins/installer