Update console_de.ts

[octaeder]

This PR resolves my Issue #1716.
I run lupdate to create an updated console_de.ts and changed translation for line 147:

    <message>
        <location filename="../mainwindow.ui" line="144"/>
        <location filename="../mainwindow.ui" line="147"/>
        <source>Documentation</source>
        <translation>Dokumentation</translation>
    </message>

[octaeder]

I could not test the translation locally because MiKTeX does not generate separate .qm files for this module, but the file validates cleanly with lrelease.

[octaeder]

    <message>
        <location filename="../mainwindow.ui" line="1708"/>
        <source>&lt;h2&gt;Documentation&lt;/h2&gt;</source>
        <translation type="unfinished"></translation>
        <translation>&lt;h2&gt;Dokumentation&lt;/h2&gt;</translation>
    </message>