references from the initial list to the headings

Runtime-Environments.md

@@ -1,18 +1,19 @@
 # Runtime Environments
 
 This page contains notes about using various runtime environments in ReCodEx as well as their internal usage inside [isolate](https://github.com/ioi/isolate) sandbox. At present ReCodEx supports
+
 * C
 * C++
-* C#
-* Data-only
-* Go
+* [C#](#c)
+* [Data-only](#data-only)
+* [Go](#go)
 * Haskell
-* Java (OpenJDK)
+* [Java (OpenJDK)](#java)
 * JavaScript (Node.js)
-* Pascal
+* [Pascal](#pascal)
 * PHP (CLI apps)
 * Prolog (SWI)
-* Python 3
+* [Python 3](#python)
 * Rust
 
 Exercises may be configured for multiple environments, so the student may choose the language for the solution. However, Data-only, Haskell, and Prolog have somewhat unique configurations, therefore an exercise must use such environment exclusively.