improve README

Author: nsiccha

README.md

@@ -1,4 +1,23 @@
 # DynamicObjects.jl
 
-Provides an `@dynamicstruct` macro, allowing quickly defining structs with cached properties. 
+Provides an `@dynamicstruct` macro, allowing quickly defining structs with derived (and optionally cached) properties, 
+which can be defined inline using `prop = expr` using all previously or afterwards defined fields and properties, e.g. as
+
+```julia
+using DynamicObjects
+
+@dynamicstruct struct MyStruct 
+    "Standard fields are defined without an `=` sign. These can have types."
+    a::Float64
+    "Derived properties can use any of the other fields or properties (provided there are no cycles)."
+    b = a + 1
+    "Derived properties can be cached."
+    @cached d = c + 1
+    "Order of definition does not matter"
+    c = b + 1
+    "Derived properties get computed lazily and then get stored locally."
+    e = d + 1
+end
+```
+
 See [https://nsiccha.github.io/DynamicObjects.jl](https://nsiccha.github.io/DynamicObjects.jl) for a non-minimal example.