Add updating instructions to the readme

README.md

@@ -11,4 +11,15 @@ Julia language binding for [cimgui](https://github.com/cimgui/cimgui)(docking br
 pkg> add LibCImGui
 ```
 
-If you are looking for a high-level Julian API you might wish to take a look at [CImGui.jl](https://github.com/Gnimuc/CImGui.jl).
+If you are looking for a high-level Julian API you might wish to take a look at [CImGui.jl](https://github.com/Gnimuc/CImGui.jl).
+
+## Updating
+The bindings for the different platforms in [lib/](lib/) are generated by the
+files in [gen/](gen/). To update the bindings you'll first need to update
+`CImGuiPack_jll`, then run:
+```
+julia --project=gen generator.jl
+```
+
+The first time might take a while since it has to download artifacts for each
+platform.