Expand HISTORY entry

Author: mhauru

HISTORY.md

@@ -12,6 +12,7 @@ This release overhauls how VarInfo objects track variables such as the log joint
   - `MiniBatchContext` does not exist anymore. It can be replaced by creating and using a custom accumulator that replaces the default `LikelihoodContext`. We may introduce such an accumulator in DynamicPPL in the future, but for now you'll need to do it yourself.
   - `tilde_observe` and `observe` have been removed. `tilde_observe!!` still exists, and any contexts should modify its behaviour. We may further rework the call stack under `tilde_observe!!` in the near future.
   - `tilde_assume` no longer returns the log density of the current assumption as its second return value. We may further rework the `tilde_assume!!` call stack as well.
+  - For literal observation statements like `0.0 ~ Normal(blahblah)` we used to call `tilde_observe!!` without the `vn` argument. This method no longer exists. Rather we call `tilde_observe!!` with `vn` set to `nothing`.
   - `set/reset/increment_num_produce!` have become `set/reset/increment_num_produce!!` (note the second exclamation mark). They are no longer guaranteed to modify the `VarInfo` in place, and one should always use the return value.
   - `@addlogprob!` now _always_ adds to the log likelihood. Previously it added to the log probability that the execution context specified, e.g. the log prior when using `PriorContext`.