Documentation for cast function

Author: groue

Documentation/AssociationsBasics.md

@@ -2661,7 +2661,7 @@ Aggregates can be modified and combined with Swift operators:
     let request = Team.annotated(with: Team.players.min(Column("score")) ?? 0)
     ```
 
-- SQL functions `ABS` and `LENGTH` are available as the `abs` and `length` Swift functions:
+- SQL functions `ABS`, `CAST`, and `LENGTH` are available as the `abs`, `cast`, and `length` Swift functions:
 
     <details>
         <summary>SQL</summary>

README.md

@@ -4291,6 +4291,17 @@ GRDB comes with a Swift version of many SQLite [built-in functions](https://sqli
 
     For more information about the functions `dateTime` and `julianDay`, see [Date And Time Functions](https://www.sqlite.org/lang_datefunc.html).
 
+- `CAST`
+
+    Use the `cast` Swift function:
+    
+    ```swift
+    // SELECT (CAST(wins AS REAL) / games) AS successRate FROM player
+    Player.select((cast(winsColumn, as: .real) / gamesColumn).forKey("successRate"))
+    ```
+    
+    See [CAST expressions](https://www.sqlite.org/lang_expr.html#castexpr) for more information about SQLite conversions.
+
 - `IFNULL`
 
     Use the Swift `??` operator: