title: Pandas drop rows appearing above/below string match
body: <p>I have a dataframe from a .txt file, and I am only interested in the data that appears between the <code>&lt;Header&gt;</code> tags.</p>
  <pre><code>          0          1  
  0 webmaster      @.com
  1  &lt;Header&gt;     121112
  2  ReportID       5353
  3      Date   20210630
  4      Type      DMV13
  5 &lt;/Header&gt;       None
  6       ZIP      90279
  7     State         WV
  </code></pre>
  <p>I therefore want to drop all other rows, but can't do it on position because the <code>&lt;Header&gt;</code> tags appear in different rows depending on the file. So is there a way to drop every row above/below a string match, so that the output looks like:</p>
  <pre><code>          0          1  
  0  ReportID       5353
  1      Date   20210630
  2      Type      DMV13
  </code></pre>