Reference solutions

Rewritten-docs.md

@@ -1765,8 +1765,8 @@ support for some common features of desktop browsers. For us in this stage of
 development is not possible to fine tune the interface for major mobile browsers
 on all mobile platforms. However, it is confirmed to work with latest Google
 Chrome and Gello browser on Android 7.1+. There are reported some issues with
-Firefox which may be fixed in future. Currently there are no data for iOS as
-nobody of us uses Apple devices.
+Firefox which may be fixed in future. Also, it is confirmed working with Safari
+browser on iOS 10.
 
 Usage of the web application is divided into the sections concerning the
 particular user roles. Under these sections all possible use cases can be found.
@@ -2239,9 +2239,22 @@ longer be available.
 
 ### Exercise's reference solutions
 
-@todo: Describe the form and explain the concept of reference solutions.
-How to evaluate the reference solutions for the exercise right now (to
-get the up-to-date information).
+Each exercise should have a set of reference solutions, which are used to tune
+time and memory limits of assignments. Values of used time and memory for each
+solution are displayed in yellow boxes under forms for setting assignment limits
+as described earlier.
+
+However, there is curretly no user interface to upload and evaluate reference
+solutions. It is possible to use direct REST API calls, but it is not much user
+friendly. If you are interested, please look at [API
+documentation](https://recodex.github.io/api/), notably sections
+_Uploaded-Files_ and _Reference-Exercise-Solutions_. You need to upload the
+reference solution files, create a new reference solution and then evaluate the
+solution. After that, measured data will be available in the box at assignment
+editing page (setting limits section).
+
+We are now working on better user interface, which will be available soon. Then
+the description will be added here.
 
 
 ## Group administrator