"Design 2nd level "mission" page"

Reordered the 2nd level mission page somewhat. I thought of a major structuring into

• Motivation (text to be updated)
• Publications incl Reports, Documentation
• Partners
• Internal structure
• Governance

Revisions on content still needed. Anyhow @frust45 , could you perhaps check for some nicely looking side-pics for the 4 subsections...? And, any formatting to make it look nicer appreciated.

Closes #11 (closed)

_layouts/frontpage.html

@@ -48,7 +48,7 @@
                                 labore et dolore magna aliqua.</p>
                         </div>
                         <div class="info-box">
-                            <a href="{% link mission/index.md %}" class="btn btn-outline-primary">
+                            <a href="{% link mission/index.html %}" class="btn btn-outline-primary">
                                 <h3><i class="fas fa-atom" aria-hidden="true"></i>&nbsp; HIFIS Mission</h3>
                             </a>
                             <p>Strengthening and developing the ICT competences of the whole Helmholtz Association.</p>