Motivation:
1. The docs about the 'retun value' of the method `io.netty.util.internal.MathUtil#isOutOfBounds` is not correct.
2. The capacity parameter should be checked for overflowed case.
Modification:
1. Changed the doc to:
> @return {@code false} if the requested {@code index} and {@code length} will fit within {@code capacity}.
> {@code true} if this would result in an index out of bounds exception.
2. Improved the bounder checking logic.
Result:
Fixes#11279Fixes#11280
11de7b65c1