put repo link in documentation

Author: pbayer

src/DiscreteEvents.jl

@@ -12,6 +12,8 @@
 A Julia package for generating and simulating discrete events. It runs on Julia
 `VERSION ≥ v"1.0"`. Multithreading requires `VERSION ≥ v"1.3"`.
 
+Its Github repo is [https://github.com/pbayer/DiscreteEvents.jl].
+
 The current stable, registered version is installed with
 ```julia
 pkg> add DiscreteEvents