Add roles of former team members

docs/authors.md

@@ -3,18 +3,18 @@
 | Name | Role |
 | ------ | ------ |
 | Vít Baisa | tech lead |
-| Jindřich Burget | TODO |
+| Jindřich Burget | frontend developer |
 | Pavel Čeleda | project manager |
 | Roman Dvořák | backend developer |
 | Richard Glosner | backend developer |
 | Tomáš Hájek | exercise designer |
-| Martin Hofbauer | TODO |
+| Martin Hofbauer | devops, research assistant |
 | Martin Horák | TODO |
 | Martin Juhás | TODO |
 | Michal Krejčíř | exercise designer |
 | Adam Parák | TODO |
 | Katarína Platková | TODO |
 | Valdemar Švábenský | TODO |
-| Michal Urban | TODO |
+| Michal Urban | lead developer of the first prototype |
 | Marek Veselý | TODO |
 | Jan Vykopal | pricipal investigator |