little nitpicks

Rewritten-docs.md

@@ -216,7 +216,9 @@ presented grouped by categories.
 
 - _a database of exercises_ -- teachers should be able to filter viewed
   exercises according to several criteria, for example supported runtime
-  environment or author
+  environment or author. It should also be possible to link exercises to a group
+  so that groups supervisors do not have to browse hundreds of exercises when
+  their group only uses five of them
 - _advanced exercises_ -- the system should support more advanced evaluation
   pipeline than basic compilation/execution/evaluation which is in CodEx
 - _customizable grading system_ -- teachers need to specify the way of
@@ -269,8 +271,8 @@ presented grouped by categories.
 
 - _no installation_ -- the primary user interface of the system must be
   accessible on the computers of the users without the need to install any
-  additional software except for a web browser (which is mostly already
+  additional software except for a web browser (which is installed on a vast
-  installed)
+  majority of personal computers)
 - _performance_ -- the system must be ready for at least hundreds of students
   and tens of supervisors using it at once
 - _automated deployment_ -- all of the components of the system must be easy to