Update docs/development.rst

Co-authored-by: Peter Ralph <[email protected]>

Author: gregorgorjanc

docs/development.rst

@@ -1166,7 +1166,7 @@ The first eight attributes are quite straightforward:
   before you set the mutation rate to ``None``.
 
 * ``recombination_rate`` (`double`): The recombination rate assumed during the inference
-  of this demographic model (per bp per generation).
+  of this demographic model, if any (per bp per generation).
   While demographic model inference might make less assumptions about recombination rates
   than mutation rates, we provide this option for completness.
   Namely, a demographic model might have been inferred under the assumption of a specific