add some literature background

DhairyaLGandhi · DhairyaLGandhi · commit 21da4f48c03d · 2021-07-11T19:01:41.000+05:30
diff --git a/docs/src/models/functors.md b/docs/src/models/functors.md
@@ -2,6 +2,8 @@
 
 Flux makes use of the Functors.jl to represent many of the core functionalities it provides.
 
+Functors.jl is a collection of tools designed to represent a [functor](https://en.wikipedia.org/wiki/Functor_(functional_programming)). Flux makes use of it to treat certain structs as functors. Notable examples include the layers that Flux defines.
+
 ```@docs
 Functors.isleaf
 Functors.children
