docs: robots.txt update

Author: peterpeterparker

studio/CHANGELOG.md

@@ -7,6 +7,7 @@
 - goodfirms featured story ([#1033](https://github.com/deckgo/deckdeckgo/pull/1033))
 - avatar display and size in menu ([#1029](https://github.com/deckgo/deckdeckgo/pull/1029))
 - display brand name in navigation offline ([#1025](https://github.com/deckgo/deckdeckgo/pull/1025))
+- update robots.txt ([#1030](https://github.com/deckgo/deckdeckgo/issues/1030))
 
 # 3.2.0 (2020-11-28)