Update README.md

Author: rcalago

core-java-modules/core-java-numbers-8/README.md

@@ -4,4 +4,5 @@
 - [Check if a Number Is Power of 2 in Java](https://www.baeldung.com/java-check-number-power-of-two)
 - [Finding the Next Higher Number With the Same Digits](https://www.baeldung.com/java-next-higher-number-same-digits)
 - [Convert Decimal to Fraction in Java](https://www.baeldung.com/java-decimal-fraction-conversion)
+- [Calculate One’s Complement of a Number](https://www.baeldung.com/java-ones-complement)
 - More articles: [[<-- prev]](../core-java-numbers-7)