You are looking at the HTML representation of the XML format.
HTML is good for debugging, but is unsuitable for application use.
Specify the format parameter to change the output format.
To see the non HTML representation of the XML format, set format=xml.
See the complete documentation, or API help for more information. 
<?xml version="1.0"?>
<api>
  <warnings>
    <main xml:space="preserve">Unrecognized parameter: '*'</main>
  </warnings>
  <query-continue>
    <revisions rvcontinue="12990" />
  </query-continue>
  <query>
    <pages>
      <page pageid="1" ns="0" title="Main Page">
        <revisions>
          <rev user="Trox" timestamp="2017-12-31T12:03:09Z" comment="/* Recent News Fab Labs as found by Google */ feed template added as per https://www.mediawiki.org/wiki/Extension_talk:RSS" />
          <rev user="Trox" timestamp="2017-12-31T11:50:31Z" comment="/* Recent News Fab Labs as found by Google */ changed over to new style Google RSS feed" />
          <rev user="Hanndoddi" timestamp="2015-09-10T13:13:14Z" comment="fixgoogle" />
          <rev user="Madouc" timestamp="2014-08-14T13:33:24Z" comment="/* Recent Changes (includes new users) */" />
          <rev user="Madouc" timestamp="2014-01-29T22:34:44Z" comment="currently showing rss breaks the front page. google news-feed therefore disabled" />
        </revisions>
      </page>
    </pages>
  </query>
</api>