alter "Learning Flux" section to match

Author: mcabbott

docs/src/index.md

@@ -18,11 +18,11 @@ Other closely associated packages, also installed automatically, include [Zygote
 
 The [quick start](@ref man-quickstart) page trains a simple neural network.
 
-This rest of this documentation provides a from-scratch introduction to Flux's take on models and how they work, starting with [fitting a line](@ref man-overview). Once you understand these docs, congratulations, you also understand [Flux's source code](https://github.com/FluxML/Flux.jl), which is intended to be concise, legible and a good reference for more advanced concepts.
+This rest of the **guide** provides a from-scratch introduction to Flux's take on models and how they work, starting with [fitting a line](@ref man-overview). Once you understand these docs, congratulations, you also understand [Flux's source code](https://github.com/FluxML/Flux.jl), which is intended to be concise, legible and a good reference for more advanced concepts.
 
-Sections with 📚 contain API listings. The same text is avalable at the Julia prompt, by typing for example `?gpu`.
+The **reference** section contains API listings. The same text is avalable at the Julia prompt, by typing for example `?gpu`.
 
-If you just want to get started writing models, the [model zoo](https://github.com/FluxML/model-zoo/) gives good starting points for many common ones.
+There are some **tutorials** about building particular models. The **[model zoo](https://github.com/FluxML/model-zoo/)** has starting points for many other common ones. And finally, the **[ecosystem page](ecosystem.md)** lists packages which define Flux models.
 
 ## Community