Update participants

PREPARATIONS.md

@@ -43,23 +43,23 @@ Confirmed:
 1. Angga Fuady
 2. Tooba Tabbassidaloii
 3. Soheil Yousefi
+4. Rick de Leeuw
+5. Sake van Pelt
 
 Confirmed (but only if seats available):
 
 1. Magnus Palmblad
 2. Arzu Tugce Guler
+3. Jonathan Vis
 
 Not yet confirmed (but with precedence):
 
 1. Saeed Katiraei
-2. Rick de Leeuw
-3. Roel Zinkstok (ONCO)
-4. Martijn Eenink (ONCO)
-5. Tarek Malas
-6. Jonathan Vis
-7. Thomas Chin-A-Woeng
-8. Sake (?)
-9. Niels (?)
+2. Roel Zinkstok (ONCO)
+3. Martijn Eenink (ONCO)
+4. Tarek Malas
+5. Thomas Chin-A-Woeng
+6. Niels (?)
 
 Remote: