Inclue RHS factResult after condition evaluation

We are using the functionality to allow the LHS attribute to be compared to a RHS attribute (demonstrated in [this example](https://github.com/CacheControl/json-rules-engine/blob/90272d61ed7bea8b7d4000305511e932490d2e2e/examples/08-fact-comparison.js)) but noticed that in the rule result, only the LHS factResult is included. Would it be possible to also include the RHS factResult? I am not too familiar with the code but it seems like the logic is contained below

https://github.com/CacheControl/json-rules-engine/blob/90272d61ed7bea8b7d4000305511e932490d2e2e/src/rule.js#L207-L212

and a logic statement along the lines of
`if (condition.value is an object) condition.value.factResult = evaluationResult.rightHandSideValue`
could be added?

If there are no issues with this I am happy to open a PR

Beginne mit src/rule.js bei den Zeilen 207-212 und vergleiche sein Verhalten mit examples/08-fact-comparison.js. Verfolge, wie die Auswertung der Bedingung das Regelergebnis aufbaut, und überprüfe anschließend, dass ein rechtsseitiges factResult zusätzlich zum bestehenden linksseitigen Ergebnis enthalten ist.

Vom Indexierungsmodell aus dem Issue-Text verfasst.