add note which versions were used for docs (#598)

docs/src/index.md

@@ -29,6 +29,27 @@ CairoMakie.activate!()
 - Check out how to make more complex plots and layouts in the [Layout Tutorial](@ref)
 - See example plots in the [Gallery](http://juliaplots.org/MakieReferenceImages/gallery/index.html).
 
+```@eval
+using Markdown
+using Pkg
+
+function print_dep_version(depname)
+    deps = Pkg.dependencies()
+    version = first(d for d in deps if d.second.name == depname).second.version
+
+    "$depname: v$version"
+end
+
+Markdown.parse("""
+!!! note
+    These docs were autogenerated using:
+      - $(print_dep_version("AbstractPlotting"))
+      - $(print_dep_version("GLMakie"))
+      - $(print_dep_version("CairoMakie"))
+    
+    If you encounter errors with the code examples, check first that your installed versions are appropriate.
+""")
+```
 
 ## Makie Ecosystem