[LANG-1511] SystemUtils is missing important documentation

Javadoc fix

Author: garydgregory

src/main/java/org/apache/commons/lang3/SystemUtils.java

@@ -2203,7 +2203,7 @@ public static boolean isJavaAwtHeadless() {
     /**
      * Tests whether the Java version at least the requested version.
      * <p>
-     * The result is based on the system property saved in {@value #JAVA_SPECIFICATION_VERSION}.
+     * The result is based on the system property saved in {@link #JAVA_SPECIFICATION_VERSION}.
      * </p>
      *
      * @param requiredVersion the required version, for example 1.31f
@@ -2216,7 +2216,7 @@ public static boolean isJavaVersionAtLeast(final JavaVersion requiredVersion) {
     /**
      * Tests whether the Java version at most the requested version.
      * <p>
-     * The result is based on the system property saved in {@value #JAVA_SPECIFICATION_VERSION}.
+     * The result is based on the system property saved in {@link #JAVA_SPECIFICATION_VERSION}.
      * </p>
      *
      * @param requiredVersion the required version, for example 1.31f