updated course year to 2020

mkdocs.yml

@@ -6,7 +6,7 @@ site_description: |
   Lecture notes for the TU Delft course TN2844 Solid state physics
 nav:
   - Preface: 'index.md'
-  - Delft 2019 course run:
+  - Delft 2020 course run:
     - Organization: 'delft.md'
     - Announcements: 'announcements.md'
   - Phonons and specific Heat:

src/delft.md

-# Delft 2019 course run
+# Delft 2020 course run
 
-The 2019 run of the TN2844 course *Vaste Stof Fysica* is now over. The retake exams will take place July 4.
+Welcome to the 2020 run of the solid state physics course (TN2844)
 
 ## Discussion chat