Swift: Fix some inconsistencies.

Author: geoffw0

swift/ql/lib/codeql/swift/elements/expr/BooleanLiteralExpr.qll

@@ -1,7 +1,7 @@
 private import codeql.swift.generated.expr.BooleanLiteralExpr
 
 /**
- * An integer literal. For example `true` in:
+ * A boolean literal. For example `true` in:
  * ```
  * let x = true
  * ```

swift/ql/lib/codeql/swift/elements/expr/FloatLiteralExpr.qll

@@ -2,4 +2,6 @@ private import codeql.swift.generated.expr.FloatLiteralExpr
 
 class FloatLiteralExpr extends Generated::FloatLiteralExpr {
   override string toString() { result = this.getStringValue() }
+
+  override string getValueString() { result = this.getStringValue() }
 }