"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)