Update pre-trade-processing.md

Author: chrisisla

docs/pre-trade-processing.md

@@ -325,7 +325,7 @@ pertain to the overall request should be specified.
 type SecurityLocate extends AvailableInventory:
 ```
 
-_Note: ```SecurityLocate``` is an extension of ```AvailabilityRecord``` and 
+_Note: ```SecurityLocate``` is an extension of ```AvailableInventory``` and 
 thus inherits all the data points from within it._
 
 ``` Haskell