message: fix(doc): fix two typos
diff: <h3>Setting up the bootstrap version manually</h3>
  - <p>Sometimes, your project might contain some library that could interfear with the bootstrap framework, or you might have a customized version of bootstrap. The consequence is that the process of determining bootstrap version might be failed, which can break the UI. In that case, we can still set the bootstrap version manually in the boostraping component (i.e. <code>AppComonent</code>):</p>
  + <p>Sometimes, your project might contain some library that could interfere with the bootstrap framework, or you might have a customized version of bootstrap. The consequence is that the process of determining bootstrap version might be failed, which can break the UI. In that case, we can still set the bootstrap version manually in the bootstrapping component (i.e. <code>AppComonent</code>):</p>
  <pre class="prettyprint lang-js prettyprinted">
  <span class="kwd">import</span><span class="pln"> </span><span class="pun">{{'{'}}</span><span class="pln"> setTheme </span><span class="pun">{{'}'}}</span><span class="pln"> from </span><span class="str">'ngx-bootstrap/utils'</span><span class="pun">;</span>
  