updated scaler readme to be less pedantic (#123)

Co-authored-by: Jason Pack <jason.pack@getcruise.com>

scaler/README.md

@@ -51,8 +51,11 @@ The Scaler component supports three scaling methods out of the box:
 
 * [LINEAR](scaler-core/scaling-methods/linear.js): This method suggests
  adding or removing nodes or processing units calculated with a simple
- linear [cross multiplication][cross-multiplication]. This way, the new
- number of nodes or processing units is
+ linear [cross multiplication][cross-multiplication].
+ In other words, the new number of processing units divided by the max
+ number of processing units is equal to the metric value divided by the
+ metric threshold value.
+ Using this method, the new number of nodes or processing units is
  [directly proportional][directly-proportional] to the current resource
  utilization.
 
@@ -139,4 +142,4 @@ The parameters `minNodes`, `maxNodes` and `currentNodes` are deprecated.
 [autoscaler-poller-parameters]: ../poller/README.md#configuration-parameters
 [spanner-regional]: https://cloud.google.com/spanner/docs/instances#configuration
 [directly-proportional]: https://en.wikipedia.org/wiki/Proportionality_(mathematics)#Direct_proportionality
-[cross-multiplication]: https://en.wikipedia.org/wiki/Cross-multiplication
+[cross-multiplication]: https://github.com/cloudspannerecosystem/autoscaler/blob/83ed3f5d37eceedd031ff679c1f2b9de7b0a3dbf/scaler/scaler-core/scaling-methods/linear.js#L35