docs(spdx-utils): Refer to SpdxSimpleLicenseMapping in normalize()

While at it, also mention `isValid` in addition to `validate`.

Signed-off-by: Sebastian Schuberth <sebastian@doubleopen.org>

utils/spdx/src/main/kotlin/SpdxExpression.kt

@@ -107,10 +107,9 @@ sealed class SpdxExpression {
         }
 
     /**
-     * Normalize all license IDs using a mapping containing common misspellings of license IDs. If [mapDeprecated] is
-     * `true`, also deprecated IDs are mapped to their current counterparts. The result of this function is not
-     * guaranteed to contain only valid IDs. Use [validate] to check the returned [SpdxExpression] for validity
-     * afterwards.
+     * Normalize all license IDs using [SpdxSimpleLicenseMapping]. If [mapDeprecated] is `true`, also deprecated IDs are
+     * mapped to their current counterparts. The result of this function is not guaranteed to contain only valid IDs.
+     * Use [validate] or [isValid] to check the returned [SpdxExpression] for validity afterwards.
      */
     abstract fun normalize(mapDeprecated: Boolean = true): SpdxExpression