Fix use of addlogprob for log prior

Author: mhauru

usage/modifying-logprob/index.qmd

@@ -47,13 +47,10 @@ using LinearAlgebra
 end
 ```
 
-Note that `@addlogprob!` always increases the accumulated log probability, regardless of the provided
-sampling context.
-For instance, if you do not want to apply `@addlogprob!` when evaluating the prior of your model but only when computing the log likelihood and the log joint probability, then you should [check the type of the internal variable `__context_`](https://github.com/TuringLang/DynamicPPL.jl/issues/154), as in the following example:
+Note that `@addlogprob!` increases the accumulated log likelihood.
+If instead you want to add to the log prior, you can use
 
 ```{julia}
 #| eval: false
-if DynamicPPL.leafcontext(__context__) !== Turing.PriorContext()
-    @addlogprob! myloglikelihood(x, μ)
-end
+@addlogprob! (; logprior=value_goes_here)
 ```